Some patients have a few or no histopathologic abnormalities. Histological examination of a biopsy may show an increase in the number and size of capillaries and veins (rarely lymphatics), dilated capillaries located in the deeper dermis, and hyperplasia and swollen endothelial cells with occasional dilated veins and venous lakes.

The prognosis is favorable in most patients with an isolated cutaneous abnormality. In the majority of cases, both the vivid red marking and the difference in circumference of the extremities regress spontaneously during the first year of life. It is theorized that this may be due to the normal maturation process, with thickening of the epidermis and dermis. Improvements for some patients can continue for up to 10 years, while in other cases, the marbled skin may persist for the patient's lifetime.

One study reported an improvement in lesions in 46% of patients within 3 years. If CMTC persists into adulthood, it can result in complaints due to paresthesia, increased sensitivity to cold and pain, and the formation of ulcers.

Few reports included long-term follow up of CMTC into adolescence and adulthood. While about 50% of patients seem to show definite improvement in the reticular vascular pattern, the exact incidence and cause of persistent cases are unknown.

Diagnostic techniques:

- antibodies (IgG) precipitates complement (C3) in the lamina lucida of the basement membrane.

- Circulating auto-antibodies to BP-1 antigen (located in hemidesmosome). 50% have BP-2.

- Positive Nikolsky sign.

- IgG, C3 deposition at BM creating smooth line in immunofluorescent analysis.

These are localized white spots on skin which may affect any area of the body, but these white spots are quite stable lesions. In the majority of patients, the lesions are not completely achromic, but are hypopigmented and resemble splashed paint. The individual lesions are permanent and there are no effective therapies for re-pigmenting this nevus. If there is hair in an affected area, it is usually colourless or white.

Diagnosis is confirmed histologically by tissue biopsy. Hematoxylin-eosin stain of biopsy slide will show features of Langerhans Cell e.g. distinct cell margin, pink granular cytoplasm. Presence of Birbeck granules on electron microscopy and immuno-cytochemical features e. g. CD1 positivity are more specific. Initially routine blood tests e.g. full blood count, liver function test, U&Es, bone profile are done to determine disease extent and rule out other causes. Radiology will show osteolytic bone lesions and damage to the lung. The latter may be evident in chest X-rays with micronodular and interstitial infiltrate in the mid and lower zone of lung, with sparing of the Costophrenic angle or honeycomb appearance in older lesions. MRI and CT may show infiltration in sella turcica. Assessment of endocrine function and bonemarrow biopsy are also performed when indicated.

- S-100 protein is expressed in a cytoplasmic pattern

- peanut agglutinin (PNA) is expressed on the cell surface and perinuclearly

- major histocompatibility (MHC) class II is expressed (because histiocytes are macrophages)

- CD1a

- langerin (CD207), a Langerhans Cell–restricted protein that induces the formation of Birbeck granules and is constitutively associated with them, is a highly specific marker.

DPN is not a premalignant condition nor is it associated with any underlying systemic disease. DPN lesions show no tendency to regress spontaneously, and often increase in size and number as an individual ages.

Definitive diagnosis of TEN often requires biopsy confirmation. Histologically, early TEN shows scattered necrotic keratinocytes. In more advanced TEN, full thickness epidermal necrosis is visualized, with a subepidermal split, and scant inflammatory infiltrate in the papillary dermis. Epidermal necrosis found on histology is sensitive but not specific finding for TEN.

The "Severity of Illness Score for Toxic Epidermal Necrolysis" (SCORTEN) is a scoring system developed to assess the severity of TEN and predict mortality in patients with acute TEN.

One point is given for each of the following factors:

- age >40

- heart rate >120 beats/minute

- carrying diagnosis of cancer

- separation of epidermis on more than ten percent of body surface area (BSA) on day 1.

- Blood Urea Nitrogen >28 mg/dL

- Glucose >252 mg/dL (14 mmol/L)

- Bicarbonate <20mEq/L

These include:

- "Generalized atrophic benign epidermolysis bullosa" is a skin condition that is characterized by onset at birth, generalized blisters and atrophy, mucosal involvement, and thickened, dystrophic, or absent nails.

- "Mitis junctional epidermolysis bullosa" (also known as "Nonlethal junctional epidermolysis bullosa") is a skin condition characterized by scalp and nail lesions, also associated with periorificial nonhealing erosions. Mitis junctional epidermolysis bullosa is most commonly seen in children between the ages of 4 and 10 years old.

- "Cicatricial junctional epidermolysis bullosa" is a skin condition characterized by blisters that heal with scarring. It was characterized in 1985.

In 2015, an Italian team of scientists, led by Michele De Luca at the University of Modena, successfully treated a seven-year-old Syrian boy who had lost 80% of his skin. The boy's family had fled Syria for Germany in 2013. Upon seeking treatment in Germany, he had lost the epidermis from almost his entire body, with only his head and a patch on his left leg remaining. The group of Italian scientists had previously pioneered a technique to regenerate healthy skin in the laboratory. They used this treatment on the boy by taking a sample from his remaining healthy skin and then genetically modifying the skin cells, using a virus to deliver a healthy version of the LAMB3 gene into the nuclei. The patient underwent two operations in autumn 2015, where the new epidermis was attached. The graft had integrated into the lower layers of skin within a month, curing the boy. The introduction of genetic changes could increase the chances of skin cancer in other patients, but if the treatment is deemed safe in the long term, scientists believe the approach could be used to treat other skin disorders.

The symptoms would appear at birth or shortly after birth. The combination of physical symptoms on the child would suggest they have CHILD syndrome. A skin sample examined under a microscope would suggest the characteristics of the syndrome and an X-Ray of the trunk, arms, and legs would help to detect underdeveloped bones. A CT scan would help detect problems of the internal organs.

Because CAPS is extremely rare and has a broad clinical presentation, it is difficult to diagnose, and a significant delay exists between symptom onset and definitive diagnosis. There are currently no clinical or diagnostic criteria for CAPS based solely on clinical presentation. Instead, diagnosis is made by genetic testing for "NLRP3" mutations. Acute phase reactants and white blood cell count are usually persistently elevated, but this is aspecific for CAPS.

Different therapeutic modalities have been attempted to repigment the lesions of nevus depigmentosus such as PUVA, excimer laser, and different grafting techniques. PUVA therapy has not been shown to be beneficial. Successful repigmentation was reported in a single case with 14 sessions of excimer laser treatment. Though the repigmentation of nevus depigmentosus is possible by grafting techniques, the results are inconsistent and recurrence is possible. In consideration of the experience of other authors and us, the quality and retention of pigment are unpredictable. These factors need to be considered while consulting and offering any treatment to the patient of nevus depigmentosus.

DPN is benign and not associated with any mortality or morbidity.

Radiologic osteosclerosis and histology are the main diagnostic features. Diagnosis can often be difficult because of the rareness of ECD as well as the need to differentiate it from LCH. A diagnosis from neurological imaging may not be definitive. The presence of symmetrical cerebellar and pontine signal changes on T2-weighted images seem to be typical of ECD, however, multiple sclerosis and metabolic diseases must also be considered in the differential diagnosis. ECD is not a common cause of exophthalmos but can be diagnosed by biopsy. However, like all biopsies, this may be inconclusive. Video-assisted thoracoscopic surgery may be used for diagnostic confirmation and also for therapeutic relief of recurrent pericardial fluid drainage.

Histologically, ECD differs from Langerhans cell histiocytosis (LCH) in a number of ways. Unlike LCH, ECD does not stain positive for S-100 proteins or Group 1 CD1a glycoproteins, and electron microscopy of cell cytoplasm does not disclose Birbeck granules. Tissue samples show xanthomatous or xanthogranulomatous infiltration by lipid-laden or foamy histiocytes, and are usually surrounded by fibrosis. Bone biopsy is said to offer the greatest likelihood of reaching a diagnosis. In some, there is histiocyte proliferation, and on staining, the section is CD68+ and CD1a-.

The management depends upon the severity of the condition. For example, where there are lesions in the mouth alone, systemic drugs are less likely to be used. Where the condition is not limited to the mouth, or where there is poor response to Topical treatments, systemic drugs are more likely to be used.

Aplasia cutis congenita (ACC) is a rare disorder characterized by congenital absence of skin. Frieden classified ACC in 1986 into 9 groups on the basis of location of the lesions and associated congenital anomalies. The scalp is the most commonly involved area with lesser involvement of trunk and extremities. Frieden classified ACC with fetus papyraceus as type 5. This type presents as truncal ACC with symmetrical absence of skin in stellate or butterfly pattern with or without involvement of proximal limbs.]It is the most common congenital cicatricial alopecia, and is a congenital focal absence of epidermis with or without evidence of other layers of the skin.

The exact etiology of ACC is still unclear but intrauterine infection by varicella or herpes virus, drugs such as methimazole, misoprostol, valproate, cocaine, marijuana etc., fetus papyraceus, feto-fetal transfusion, vascular coagulation defects, amniotic membrane adherence, abnormal elastic fiber biomechanical forces and trauma are implicated. It can be associated with Johanson-Blizzard syndrome, Adams-Oliver syndrome, trisomy 13, and Wolf-Hirschhorn syndrome.

It can also seen with exposure to methimazole and carbimazole in utero. This dermatological manifestation has been linked to Peptidase D haploinsufficiency and a deletion in Chromosome 19.

Pemphigoid is usually considered to be mediated by IgG, but IgA-mediated forms have also been described.

IgA-mediated immunobullous diseases can often be difficult to treat even with usually effective medications such as rituximab.

This condition has been linked to mutations in the ribosomal GTPase BMS1 gene.

Granuloma faciale (GF) is an uncommon benign chronic skin disease of unknown origin characterized by single or multiple cutaneous nodules, usually occurring over the face. Occasionally, extrafacial involvement is noted, most often on sun-exposed areas.

The disease mimics many other dermatoses and can be confused with conditions, such as sarcoidosis, discoid lupus erythematosus, mycosis fungoides, and fixed drug eruption.

Throughout the years, many different treatments have been tried for morphea including topical, intra-lesional, and systemic corticosteroids. Antimalarials such as hydroxychloroquine or chloroquine have been used. Other immunomodulators such as methotrexate, topical tacrolimus, and penicillamine have been tried. Some have tried prescription vitamian-D with success. Ultraviolet A (UVA) light, with or without psoralens have also been tried. UVA-1, a more specific wavelength of UVA light, is able to penetrate the deeper portions of the skin and thus, thought to soften the plaques in morphea by acting in two fashions:

- 1) by causing a systemic immunosuppression from UV light.

- 2) by inducing enzymes that naturally degrade the collagen matrix in the skin as part of natural sun-aging of the skin.

As with all of these treatments for morphea, the difficulty in assessing outcomes in an objective way has limited the interpretation of most studies involving these treatment modalities.

Physicians and scientists do not know what causes morphea. Case reports and observational studies suggest there is a higher frequency of family history of autoimmune diseases in patients with morphea. Tests for autoantibodies associated with morphea have shown results in higher frequencies of anti-histone and anti-topoisomerase IIa antibodies. Case reports of morphea co-existing with other systemic autoimmune diseases such as primary biliary cirrhosis, vitiligo, and systemic lupus erythematosus lend support to morphea as an autoimmune disease.

B burgdorferi infection may be relevant for the induction of a distinct autoimmune type of scleroderma; it may be called "Borrelia-associated early onset morphea" and is characterized by the combination of disease onset at younger age, infection with B burgdorferi, and evident autoimmune phenomena as reflected by high-titer antinuclear antibodies.

The diagnosis is based on involvement of less than 10% of the skin. It is known as TEN when more than 30% of the skin is involved and an intermediate form with 10 to 30% involvement. A positive Nikolsky's sign is helpful in the diagnosis of SJS and TEN. A skin biopsy is helpful, but not required, to establish a diagnosis of SJS and TEN.