Treatment is directed toward the underlying cause. However, in primary eosinophilia, or if the eosinophil count must be lowered, corticosteroids such as prednisone may be used. However, immune suppression, the mechanism of action of corticosteroids, can be fatal in patients with parasitosis.

Treatments used to combat autoimmune diseases and conditions caused by eosinophils include:

- corticosteroids – promote apoptosis. Numbers of eosinophils in blood are rapidly reduced

- monoclonal antibody therapy – e.g., mepolizumab or reslizumab against IL-5, prevents eosinophilopoiesis

- antagonists of leukotriene synthesis or receptors

- imatinib (STI571) – inhibits PDGF-BB in hypereosinophilic leukemia

Monoclonal antibodies such as dupilumab and lebrikizumab target IL-13 and its receptor, which reduces eosinophilic inflammation in pateints with asthma due to lowering the number of adhesion molecules present for eosinophils to bind to, thereby decreasing inflammation. Mepolizumab and benralizumab are other treatment options that target the alpha subunit of the IL-5 receptor, thereby inhibiting its function and reducing the number of developing eosinophils as well as the number of eosinophils leading to inflammation through antibody-dependent cell-mediated cytotoxicity and eosinophilic apoptosis.

Lymphocyte-variant hypereosinophilia usually takes a benign and indolent course. Long term treatment with corticosteroids lowers blood eosinophil levels as well as suppresses and prevents complications of the disease in >80% of cases. However, signs and symptoms of the disease recur in virtually all cases if corticosteroid dosages are tapered in order to reduce the many adverse side effects of corticosteroids. Alternate treatments used to treat corticosteroid resistant disease or for use as corticosteroid-sparing substitutes include interferon-α or its analog, Peginterferon alfa-2a, Mepolizumab (an antibody directed against IL-5), Ciclosporin (an Immunosuppressive drug), imatinib (an inhibitor of tyrosine kinases; numerous tyrosine kinase cell signaling proteins are responsible for the growth and proliferation of eosinophils {see clonal eosinophilia}), methotrexate and Hydroxycarbamide (both are chemotherapy and immunosuppressant drugs), and Alemtuzumab (a antibody that binds to the CD52 antigen on mature lymphocytes thereby marking them for destruction by the body). The few patients who have been treated with these alternate drugs have exhibited good responses in the majority of instances. Reslizumab, a newly developed antibody directed against interleukin 5 that has been successfully used to treat 4 patients with the hypereosinophilic syndrome, may also be of use for lymphocyte-variant eosinophilia. Patients suffering minimal or no disease complications have gone untreated.

In 10% to 25% of patients, mostly 3 to 10 years after initical diagnosis, the indolent course of lymphocyte-variant hypereosinophilia changes. Patients exhibit rapid increases in lymphadenopathy, spleen size, and blood cell numbers, some cells of which take on the appearance of immature and/or malignant cells. Their disease soon thereafter escalates to an angioimmunoblastic T-cell lymphoma, peripheral T cell lymphoma, Anaplastic large-cell lymphoma (which unlike most lymphomas of this type is Anaplastic lymphoma kinase-negative), or Cutaneous T cell lymphoma. The malignantly transformed disease is aggressive and has a poor prognosis. Recommended treatment includes chemotherapy with Fludarabine, Cladribine, or the CHOP combination of drugs followed by bone marrow transplantation.

Due to its rarity, no comprehensive treatment studies on eosinophilic myocarditis have been conducted. Small studies and case reports have directed efforts towards: a) supporting cardiac function by relieving heart failure and suppressing life-threatening abnormal heart rhythms; b) suppressing eosinophil-based cardiac inflammation; and c) treating the underlying disorder. In all cases of symptomatic eosinophilic myocarditis that lack specific treatment regimens for the underlying disorder, available studies recommend treating the inflammatory component of this disorder with non-specific immunosuppressive drugs, principally high-dosage followed by slowly-tapering to a low-dosage maintenance corticosteroid regimens. It is recommended that afflicted individuals who fail this regimen or present with cardiogenic shock be treated with other non-specific immunosuppressive drugs viz., azathioprine or cyclophosphamide, as adjuncts to, or replacements for, corticosteroids. However, individuals with an underlying therapeutically accessible disease should be treated for this disease; in seriously symptomatic cases, such individuals may be treated concurrently with a corticosteroid regimen. Examples of diseases underlying eosinophilic myocarditis that are recommended for treatments directed at the underlying disease include:

- Infectious agents: specific drug treatment of helminth and protozoan infections typically takes precedence over non-specific immunosuppressive therapy, which, if used without specific treatment, could worsen the infection. In moderate-to-severe cases, non-specific immunosuppression is used in combination with specific drug treatment.

- Toxic reactions to ingested agents: discontinuance of the ingested agent plus corticosteroids or other non-specific immunosuppressive regimens.

- Clonal eosinophilia caused by mutations in genes that are highly susceptible to tyrosine kinase inhibitors such as "PDGFRA", "PDGFRB", or possibly "FGFR1": first generation tyrosine kinase inhibitors (e.g. imatinib) are recommended for the former two mutations; a later generation tyrosine kinase inhibitors, ponatinib, alone or combined with bone marrow transplantation, may be useful for treating the FGFR1 mutations.

- Clonal hypereosinophilia due to mutations in other genes or primary malignancies: specific treatment regimens used for these pre-malignant or malignant diseases may be more useful and necessary than non-specific immunosuppression.

- Allergic and autoimmune diseases: non-specific treatment regimens used for these diseases may be useful in place of a simple corticosteroid regimen. For example, eosinophilic granulomatosis with polyangiitis can be successfully treated with mepolizumab.

- Idiopathic hypereosinphilic syndrome and lymphocyte-variant hypereosinophilia: corticosteroids; for individuals with these hypereosinophilias that are refractory to or break through corticosteroid therapy and individuals requiring corticosteroid-sparing therapy, recommended alternative drug therapies include hydroxyurea, Pegylated interferon-α, and either one of two tyrosine kinase inhibitors viz., imatinib and mepolizumab).

A wide range of drugs are known to cause hypereosinophilia or eosinophilia accompanied by an array of allergic symptoms. Rarely, these reactions are severe causing, for example, the drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. While virtually any drug should be considered as a possible cause of these signs and symptoms, the following drugs and drug classes are some of the most frequently reported causes: penicillins, cephalosporins, dapsone, sulfonamides, carbamazepine, phenytoin, lamotrigine, valproic acid, nevirapine, efavirenz, and ibuprofen. These drugs may cause severely toxic reactions such as the DRESS syndrome. Other drugs and drug classes often reported to cause increased blood eosinophil levels accompanied by less severe (e.g. non-DRESS syndrome) symptoms include tetracyclins, doxycycline, linezolid, nitrofurantoin, metronidazole, carbamazepine, phenobarbital, lamotrigine, valproate, desipramine, amitriptyline, fluoxetine, piroxicam, diclofenac, ACE inhibitors, abacavir, nevirapine, ranitidine, cyclosporin, and hydrochlorothiazide.

The toxic oil syndrome is associated with hypereosinophilia/eosinophilia and systemic symptoms due to one or more contaminants in rapeseed oil and the Eosinophilia–myalgia syndrome, also associated with hypereosinophilia, appears due to trace contaminants in certain commercial batches of the amino acid, L-tryptophan.

Eosinophilia and comparatively fewer cases of hypereosinophilia are associated with the following known diseases that are known or thought to have an allergic basis: allergic rhinitis, asthma, atopic dermatitis, eosinophilic esophagitis, chronic sinusitis, aspirin-induced asthma, allergic bronchopulmonary aspergillosis, chronic eosinophilic pneumonia, and Kimura's disease.

Certain types of food allergy disorders may also be associated with eosinophilia or, less commonly, hypereosinophilia. Allergic eosinophilic esophagitis and the Food protein-induced enterocolitis syndrome are commonly associated with increased blood eosinophil levels.

Allergic reactions to drugs are a common cause of eosinophilia, with manifestations ranging from diffuse maculopapular rash, to severe life-threatening drug reactions with eosinophilia and systemic symptoms (DRESS). Drugs that have been shown to cause DRESS are aromatic anticonvulsants and other antiepileptics, sulfonamides, allopurinol, nonsteroidal anti-inflammatory drugs (NSAIDs), some antipsychotics such as risperidone, and certain antibiotics. Phenibut, an analogue of the neurotransmitter GABA, has also been implicated in high doses. The reaction which has been shown to be T-cell mediated may also cause eosinophilia-myalgia syndrome.

Lymphocyte-variant hypereosinophila, also termed lymphocyte variant eosinophilia, is a rare disorder in which eosinophilia or hypereosinophilia (i.e. a large or extremely large increase in the number of eosinophils in the blood circulation) is caused by aberrant population of lymphocytes. These aberrant lymphocytes function abnormally by stimulating the proliferation and maturation of bone marrow eosinophil-precursor cells termed colony forming unit-Eosinophils or CFU-Eos.

The overly stimulated CFU-Eos cells mature to apparently normal eosinophils, enter the circulation, and may accumulate in, and severely damage, various tissues. The disorder is usually indolent or slowly progressive but may proceed to a leukemic phase and at this phases is sometimes classified as acute eosinophilic leukemia. Hence, lymphocyte-variant hypereosinophilia can be regarded as a precancerous disease.

The order merits therapeutic intervention to avoid or reduce eosinophil-induced tissue injury and to treat its leukemic phase. The latter phase of the disease is aggressive and typically responds relatively poorly to anti-leukemia chemotherapeutic drug regimens.

Corticosteroids are the mainstay of therapy with a 90% response rate in some studies. Appropriate duration of steroid treatment is unknown and relapse often necessitates long term treatment. Various steroid sparing agents e.g. sodium cromoglycate (a stabilizer of mast cell membranes), ketotifen (an antihistamine), and montelukast (a selective, competitive leukotriene receptor antagonist) have been proposed, centering on an allergic hypothesis, with mixed results. An elimination diet may be successful if a limited number of food allergies are identified.

Most patients with "ETV6-ACSL6"-related disease present with findings similar to eosinophilia, hypereosinophila, or chronic eosinophilic leukemia; at least 4 cases presented with eosinophilia plus findings of the red blood cell neoplasm, polycythemia vera; three cases resembled acute myelogenous leukemia; and one case presented with findings of a combined Myelodysplastic syndrome/myeloproliferative neoplasm. Best treatments for "ETV6-ACSL6"-related disease are unclear. Patients with the polycythemia vera form of the disease have been treated by reducing the circulating red blood cell load by phlebotomy or suppressing red blood cell formation using hydroxyurea. Individual case studies report that "ETV6-ACSL6"-associated disease is insensitive to tyrosine kinase inhibitors. Best treatment currently available, therefore, may involve chemotherapy and bone marrow transplantion.

Treatment for eosinophilic granulomatosis with polyangiitis includes glucocorticoids (such as prednisolone) and other immunosuppressive drugs (such as azathioprine and cyclophosphamide). In many cases, the disease can be put into a type of chemical remission through drug therapy, but the disease is chronic and lifelong.

A systematic review conducted in 2007 indicated all patients should be treated with high-dose steroids, but in patients with a five-factor score of one or higher, cyclophosphamide pulse therapy should be commenced, with 12 pulses leading to fewer relapses than six. Remission can be maintained with a less toxic drug, such as azathioprine or methotrexate.

On December 12, 2017, the FDA approved mepolizumab, the first drug therapy specifically indicated for the treatment of eosinophilic granulomatosis with polyangiitis. Patients taking mepolizumab experienced a "significant improvement" in their symptoms.

Within the fat (adipose) tissue of CCR2 deficient mice, there is an increased number of eosinophils, greater alternative macrophage activation, and a propensity towards type 2 cytokine expression. Furthermore, this effect was exaggerated when the mice became obese from a high fat diet.

Mouse models of eosinophilia from mice infected with T canis showed an increase in IL-5 mRNA in mice spleen. Mouse models of asthma from OVA show a higher TH2 response. When mice are administered IL-12 to induce the TH1 response, the TH2 repsonse becomes suppressed, showing that mice that do not have TH2 cytokines are significantly less likely to express asthma symptoms.

Following a successful induction of remission, maintenance therapy might be given in some cases, for example when there is a high risk of relapse or in patients with organ-threatening manifestations. Common maintenancy therapy is prednisolone 2.5–5 mg per day, or use of a steroid-sparing agent instead.

There are many causes of eosinophilia that may underlie eosinophilic myocarditis. These causes are classified as primary (i.e. a defect intrinsic to the eosinophil cell line), secondary (induced by an underlying disorder that stimulates the proliferation and activation of eosinophils), or idiopathic (i.e. unknown cause). Non-idiopathic causes of the disorder are sub-classified into various forms of allergic, autoimmune, infectious, or malignant diseases and hypersensitivity reactions to drugs, vaccines, or transplanted hearts. While virtually any cause for the elevation and activation of blood eosinophils must be considered as a potential cause for eosinophilic myocarditis, the follow list gives the principal types of eosinophilia known or thought to underlie the disorder.

Primary conditions that may lead to eosinophilic myocarditis are:

- Clonal hypereosinophilia.

- Chronic eosinophilic leukemia.

- The idiopathic hypereosinophilic syndrome.

Secondary conditions that may lead to eosinophilic myocarditis are:

- Infections agents:

- Parasitic worms: various "Ascaris, Strongyloides, Schistosoma, filaria, Trematoda", and "Nematode" species. Parasitic infestations often cause significant heart valve disease along with myocarditis and the disorder in this setting is sometimes termed Tropical endomyocardial fibrosis. While commonly considered to be due to the cited parasites, this particular form of eosinophilic myocarditis may more often develop in individuals with other disorders, e.g. malnutrition, dietary toxins, and genetic predisposition, in addition to or place of round worm infestation.

- Infections by protozoa: various "Toxoplasma gondii, Trypanosoma cruzi, trichinella spiralis, Entamoeba", and "Echinococcus" species.

- Viruses: While some viral infections (e.g. HIV) have been considered causes of eosinophilic endocarditis, a study of 20 patients concluded that viral myocarditis lacks the characteristic of eosinophil-induced damage in hearts taken during cardiac transplantation.

- Allergic and autoimmune diseases such as severe asthma, rhinitis, or urticarial, chronic sinusitis, aspirin-induced asthma, allergic bronchopulmonary aspergillosis, chronic eosinophilic pneumonia, Kimura's disease, polyarteritis nodosa, eosinophilic granulomatosis with polyangiitis (i.e. Churg-Strauss syndrome), and rejection of transplanted hearts.

- Malignancies and/or premalignant hematologic conditions not due to a primary disorder in eosinophils such as Gleich's syndrome, Lymphocyte-variant hypereosinophilia Hodgkin disease, certain T-cell lymphomas, acute myeloid leukemia, the myelodysplastic syndromes, systemic mastocytosis, chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, myelofibrosis, chronic myelomonocytic leukemia, and T-lymphoblastic leukemia/lymphoma-associated or myelodysplastic–myeloproliferative syndrome-associated eosinophilias; IgG4-related disease and Angiolymphoid hyperplasia with eosinophilia as well as non-hematologic cancers such as solid tumors of the lung, gastrointestinal tract, and genitourinary tract.

- Hypersensitivity reactions to agents include:

- Antibiotics/anti-viral agents: various penicillins (e.g. penicillin, ampicillin), cephalosporins (e.g. cephalosporin), tetracyclins (e.g. tetracycline), sulfonamides (e.g. sulfadiazine, sulfafurazole), sulfonylureas, antituburcular drugs (e.g. isoniazid, 4-aminosalicylic acid), linezolid, amphotericin B, chloramphenicol, streptomycin, dapsone, nitrofurantoin, metronidazole, nevirapine, efavirenz, abacavir, nevirapine.

- Anticonvulsants/Antipsychotics/antidepressants: phenindione, phenytoin, phenobarbital, lamotrigine, lamotrigine, clozapine, valproic acid, carbamazepine, desipramine, fluoxetine, amitriptyline, olanzapine.

- Anti-inflammatory agents: ibuprofen, indomethacin, phenylbutazone, oxyphenbutazone, acetazolamide, piroxicam, diclofenac.

- Diuretics: hydrochlorothiazide, spironolactone, chlortalidone.

- ACE inhibitors: captopril, enalapril.

- Other drugs: digoxin, ranitidine, lenalidomide, methyldopa, interleukin 2, dobutamine, acetazolamide.

- Contaminants: Unidentified contaminants inrapeseed oil cause the toxic oil syndrome and in commercial batches of the amino acid, L-tryptophan, cause the eosinophilia–myalgia syndrome.

- Vaccinations: Tetanus toxoid, smallpox, and diphtheria/pertussis/tetanus vaccinations.

Patients with hematological disease related to the cited "FLT3" fusion genes present with either a myeloid or lymphoid neoplasm plus eosinophilia. Four of 6 patients with "ETV6-FLT3"-related disease, a patient with "GOLGB1-FLT3"-related disease, and a patient with "TRIP11-FLT3"-related disease presented with findings similar to T-cell lymphoma while a patient with "SPTBN1-FLT3"-related disease had findings of chronic myelogenous leukemia. Two patients with "ETV6-FLT3"-related disease experienced complete hematologic remissions when treated with a multi-kinase inhibitor, sunitinib, that has inhibitory activity against FLT3 protein. However, these remissions were short-lived. A third patient with "ETV6-FLT3"-related disease was treated with a similarly active kinase inhibitor, sorafenib. This patient achieved a complete hematological response and was then given a hematopoietic stem cell transplantation. The latter treatment regimen, FLT3 inhibitor followed by hematopoietic stem cell transplantation, may be the best approach currently available for treating "FLT3"-releated hematological disease.

In untreated patients with active disease, the recommended first-line agent for induction of remission is glucocorticoids unless contraindications exist. Glucocorticoids characteristically result in a rapid and often dramatic improvement in clinical features and often a resolution of radiographic features. However, where advanced fibrotic lesions have resulted in irreversible damage, the response to glucocorticoids and other current treatment options may be poor or even absent.

Although not validated yet in clinical trials, the common induction regime is prednisolone 30–40 mg per day for 2–4 weeks, then gradually tapered over 3 to 6 months. Recurrences during or after tapering of glucocorticoids are frequent however. Steroid-sparing immunosuppressive agents might be considered, depending on local availability of these drugs, for use in combination with glucocorticoids from the start of treatment. Steroid-sparing agents that have been used include rituximab, azathioprine, methotrexate, and cyclophosphamide, although trials are needed to ascertain the effectiveness of each drug in IgG4-RD.

Treatment options include:

1. Therapies to eliminate the underlying cancer, such as chemotherapy, radiation and surgery.

2. Therapies to reduce or slow neurological degeneration. In this scenario, rapid diagnosis and treatment are critical for the patient to have the best chance of recovery. Since these disorders are relatively rare, few doctors have seen or treated paraneoplastic neurological disorders (PNDs). Therefore, PND patients should consult with a specialist with experience in diagnosing and treating paraneoplastic neurological disorders.

A specific prognosis for those afflicted with paraneoplastic syndromes links to each unique case presented. Thus, prognosis for paraneoplastic syndromes may vary greatly. For example, paraneoplastic pemphigus often included infection as a major cause of death. Paraneoplastic pemphigus is one of the three major subtypes that affects IgG autoantibodies that are characteristically raised against desmoglein 1 and desmoglein 3 (which are cell-cell adhesion molecules found in desmosomes). Underlying cancer or irreversible system impairment, seen in acute heart failure or kidney failure, may result in death as well.

Eosinophilic gastroenteritis (EG) is a rare and heterogeneous condition characterized by patchy or diffuse eosinophilic infiltration of gastrointestinal (GI) tissue, first described by Kaijser in 1937. Presentation may vary depending on location as well as depth and extent of bowel wall involvement and usually runs a chronic relapsing course. It can be classified into mucosal, muscular and serosal types based on the depth of involvement. Any part of the GI tract can be affected, and isolated biliary tract involvement has also been reported.

The stomach is the organ most commonly affected, followed by the small intestine and the colon.

Eosinophilic granulomatosis with polyangiitis (EGPA; also known as Churg-Strauss syndrome [CSS] or allergic granulomatosis) is an extremely rare autoimmune condition that causes inflammation of small and medium-sized blood vessels (vasculitis) in persons with a history of airway allergic hypersensitivity (atopy).

It usually manifests in three stages. The early (prodromal) stage is marked by airway inflammation; almost all patients experience asthma and/or allergic rhinitis. The second stage is characterized by abnormally high numbers of eosinophils (hypereosinophilia), which causes tissue damage, most commonly to the lungs and the digestive tract. The third stage consists of vasculitis, which can eventually lead to cell death and can be life-threatening.

This condition is now called "eosinophilic granulomatosis with polyangiitis" to remove all eponyms from the vasculitides. To facilitate the transition, it was referred to as "eosinophilic granulomatosis with polyangiitis (Churg-Strauss)" for a period of time starting in 2012. Prior to this it was known as "Churg-Strauss syndrome", named after Drs. Jacob Churg and Lotte Strauss who, in 1951, first published about the syndrome using the term "allergic granulomatosis" to describe it. It is a type of systemic necrotizing vasculitis.

Effective treatment of EGPA requires suppression of the immune system with medication. This is typically glucocorticoids, followed by other agents such as cyclophosphamide or azathioprine.

Prostate cancer is the second most common urological malignancy to be associated with paraneoplastic syndromes after renal cell carcinoma. Paraneoplastic syndromes of this nature tend to occur in the setting of late stage and aggressive tumors with poor overall outcomes (endocrine manifestations, neurological entities, dermatological conditions, and other syndromes). A vast majority of prostate cancer cases (over 70%) document paraneoplastic syndrome as a major clinical manifestation of prostate cancer; and interestingly (under 20%), the syndrome as an initial sign of disease progression to the castrate-resistant state. Urologist researchers identify serum markers that are associated with the syndrome in order to specific what type of therapies may work most effectively.

Paraneoplastic neurological syndromes may be related immune checkpoint inhibitors (ICIs), one of the underlying causes in inflammatory central nervous system diseases (CNS). The central idea around such research pinpoints treatment strategies to combat cancer related outcomes in the clinical arena, specifically ICIs. Research suggests that patients who are treated with ICIs are more susceptible to CNS disease (since the mechanism of ICIs induces adverse effects on the CNS due to augmented immune responses and neurotoxicity). The purpose of this exploration was to shed light on immunotherapies and distinguishing between neurotoxicity and brain metastasis in the early stages of treatment. In other research, scientists have found that paraneoplastic peripheral nerve disorders (autoantibodies linked to multifocal motor neuropathy) may provide important clinical manifestations. This is especially important for patients who experience inflammatory neuropathies since solid tumors are often associated with peripheral nerve disorders. CV2 autoantibodies, which target dihydropyriminase-related protein 5 (DRP5, or CRMP5) are also associated with a variety of paraneoplastic neurological syndromes, including sensorimotor polyneuropathies. Interestingly, patients undergoing immune therapies or tumor removal respond very well to antibodies that target CASPR2 (to treat nerve hyperexcitability and neuromyotonia).

In the case of paraneoplastic Cushing's syndrome arising from a small cel carcinoma of the endometrium, paraneoplastic syndrome has been seen to interfere with standard treatments and lead to unexpected complications and clinical course. The purpose of this clinical case demonstrates the aggressive nature of the neuroendocrine small cell carcinoma with rapid invasion and extra-uterine spread. The researchers raise recognition for timely recognition of paraneoplastic syndrome, which in this particular case use a combinatorial therapy of etoposide and cisplatin chemotherapy to save the 32-year old female patient's life (presented with persistent migraine-like headache, palpitations, progressive nausea and vomiting, photo- and sonobia, menometrorrhagia and concomitant general fatigue).

Eosinophilic states that may occur in association with Loeffler endocarditis include hypereosinophilic syndrome, eosinophilic leukemia, carcinoma, lymphoma, drug reactions or parasites, as reported in multiple case series. Hypereosinophilia can be caused by a worm (helminth) that invokes the chronic persistence of these eosinophils, resulting in a condition known as hypereosinophilic syndrome.

The eosinophilia and eosinophilic penetration of the cardiac myocytes leads to a fibrotic thickening of portions of the heart (similar to that of endomyocardial fibrosis). Commonly the heart will develop large mural thrombi (thrombi which lay against ventricle walls) due to the deterioration of left ventricular wall muscle. Symptoms include edema and breathlessness. The disease is commonly contracted in temperate climates (due to the favorable conditions for parasites), and is rapidly fatal.

Loeffler endocarditis is a form of restrictive cardiomyopathy which affects the endocardium and occurs with white blood cell proliferation, specifically of eosinophils. Restrictive cardiomyopathy is defined as a disease of the heart muscle which results in impaired filling of the heart ventricles during diastole.

Many conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.

The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers by diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), etiology (skin conditions resulting from physical factors), and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow). Diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data.

Urticaria is a vascular reaction of the skin characterized by the appearance of wheals, which are firm, elevated swelling of the skin. Angioedema, which can occur alone or with

urticaria, is characterized by a well-defined, edematous swelling that involves subcutaneous tissues, abdominal organs, or upper airway.

- Acquired C1 esterase inhibitor deficiency

- Acute urticaria

- Adrenergic urticaria

- Anaphylaxis

- Aquagenic urticaria

- Cholinergic urticaria

- Chronic urticaria (ordinary urticaria)

- Cold urticaria

- Dermatographism (dermographism)

- Episodic angioedema with eosinophilia (Gleich's syndrome)

- Exercise urticaria (exercise-induced urticaria)

- Galvanic urticaria

- Heat urticaria

- Hereditary angioedema (Quincke's edema)

- Localized heat contact urticaria

- Mast cell-independent urticaria

- Physical urticaria

- Primary cold contact urticaria

- Pressure urticaria (delayed pressure urticaria)

- Reflex cold urticaria

- Schnitzler syndrome

- Secondary cold contact urticaria

- Solar urticaria

- Systemic capillary leak syndrome

- Urticarial allergic eruption

- Urticaria-like follicular mucinosis

- Vibratory angioedema

Toxocariasis will often resolve itself, because the "Toxocara" larvae cannot mature within human hosts. Corticosteroids are prescribed in severe cases of VLM or if the patient is diagnosed with OLM. Either albendazole (preferred) or mebendazole (“second line therapy”) may be prescribed. Granulomas can be surgically removed, or laser photocoagulation and cryoretinopexy can be used to destroy ocular granulomas.

Visceral toxocariasis in humans can be treated with antiparasitic drugs such as albendazole or mebendazole, tiabendazole or diethylcarbamazine usually in combination with anti-inflammatory medications. Steroids have been utilized with some positive results. Anti-helminthic therapy is reserved for severe infections (lungs, brain) because therapy may induce, due to massive larval killing, a strong inflammatory response. Treatment of ocular toxocariasis is more difficult and usually consists of measures to prevent progressive damage to the eye.