Clinically, IPH manifests as a triad of haemoptysis, diffuse parenchymal infiltrates on chest radiographs, and iron deficiency anaemia. It is diagnosed at an average age of 4.5 plus or minus 3.5 years, and it is twice as common in females. The clinical course of IPH is exceedingly variable, and most of the patients continue to have episodes of pulmonary haemorrhage despite therapy. Death may occur suddenly from acute pulmonary haemorrhage or after progressive pulmonary insufficiency resulting in chronic respiratory failure.

Idiopathic pulmonary haemosiderosis (or idiopathic pulmonary hemosiderosis; IPH) is a lung disease of unknown cause that is characterized by alveolar capillary bleeding and accumulation of haemosiderin in the lungs. It is rare, with an incidence between 0.24 and 1.23 cases per million people.

Brown induration is fibrosis and hemosiderin pigmentation of the lungs due to long standing pulmonary congestion (chronic passive congestion).

Signs that consolidation may have occurred include:

- Expansion of the thorax on inspiration is reduced on the affected side

- Vocal fremitus is increased on the side with consolidation

- Percussion is dull in affected area

- Breath sounds are bronchial

- Possible medium, late, or pan-inspiratory crackles

- Vocal resonance is increased. Here, the patient's voice (or whisper, as in whispered pectoriloquy) can be heard more clearly when there is consolidation, as opposed to in the healthy lung where speech sounds muffled.

- A pleural rub may be present.

- A lower expected Pa02 than calculated in the alveolar gas equation

A pulmonary consolidation is a region of (normally compressible) lung tissue that has filled with liquid, a condition marked by induration (swelling or hardening of normally soft tissue) of a normally aerated lung. It is considered a radiologic sign. Consolidation occurs through accumulation of inflammatory cellular exudate in the alveoli and adjoining ducts. Simply, it is defined as alveolar space that contains liquid instead of gas. The liquid can be pulmonary edema, inflammatory exudate, pus, inhaled water, or blood (from bronchial tree or hemorrhage from a pulmonary artery). It must be present to diagnose pneumonia: the signs of lobar pneumonia are characteristic and clinically referred to as consolidation.

Brown lung can ultimately result in narrowing of the airways, lung scarring and death from infection or respiratory failure.

Byssinosis, also called "brown lung disease" or "Monday fever", is an occupational lung disease caused by exposure to cotton dust in inadequately ventilated working environments. Byssinosis commonly occurs in workers who are employed in yarn and fabric manufacture industries. It is now thought that the cotton dust directly causes the disease and some believe that the causative agents are endotoxins that come from the cell walls of gram-negative bacteria that grow on the cotton. Although bacterial endotoxin is a likely cause, the absence of similar symptoms in workers in other industries exposed to endotoxins makes this uncertain.

Of the 81 byssinosis-related fatalities reported in the United States between 1990 and 1999, 48% included an occupation in the yarn, thread, and fabric industry on the victim's death certificate. This disease often occurred in the times of the industrial revolution. Most commonly young girls working in mills or other textile factories would be afflicted with this disease. In the United States, from 1996 to 2005, North Carolina accounted for about 37% of all deaths caused by byssinosis, with 31, followed by South Carolina (8) and Georgia (7).

The term "brown lung" is a misnomer, as the lungs of affected individuals are not brown.

Pain may be the first noticed symptom. People with lipodermatosclerosis have tapering of their legs above the ankles, forming a constricting band resembling an inverted champagne bottle. In addition, there may be brownish-red pigmentation and induration.

Lipodermatosclerosis (also known as "chronic panniculitis with lipomembranous changes", "hypodermitis sclerodermiformis", "sclerosing panniculitis", and "stasis panniculitis") is a skin and connective tissue disease. It is a form of lower extremity panniculitis, an inflammation of the layer of fat under the epidermis.

The first skin changes in calciphylaxis lesions are mottling of the skin and induration in a livedo reticularis pattern. As tissue thrombosis and infarction occurs, a black, leathery eschar in an ulcer with adherent black slough are found. Surrounding the ulcers is usually a plate-like area of indurated skin. These lesions are always extremely painful and most often occur on the lower extremities, abdomen, buttocks, and penis. Because the tissue has infarcted, wound healing seldom occurs, and ulcers are more likely to become secondarily infected. Many cases of calciphylaxis end with systemic bacterial infection and death.

Calciphylaxis is characterized by the following histologic findings:

1. systemic medial calcification of the arteries, i.e. calcification of tunica media. Unlike other forms of vascular calcifications (e.g., intimal, medial, valvular), calciphylaxis is characterized also by

2. small vessel mural calcification with or without endovascular fibrosis, extravascular calcification and vascular thrombosis, leading to tissue ischemia (including skin ischemia and, hence, skin necrosis).

Calciphylaxis, or calcific uremic arteriolopathy (CUA), is a syndrome of calcification of the blood vessels, blood clots, and skin necrosis. It is seen mostly in patients with stage 5 chronic kidney disease, but can occur in the absence of kidney failure. It results in chronic non-healing wounds and is usually fatal. Calciphylaxis is a rare but serious disease, believed to affect 1-4% of all dialysis patients.

Calciphylaxis is one type of extraskeletal calcification. Similar extraskeletal calcifications are observed in some patients with hypercalcemic states, including patients with milk-alkali syndrome, sarcoidosis, primary hyperparathyroidism, and hypervitaminosis D.

Pretibial myxedema is almost always preceded by the ocular signs found in Graves' disease.

It usually presents itself as a waxy, discolored induration of the skin—classically described as having a so-called "peau d'orange" (orange peel) appearance—on the anterior aspect of the lower legs, spreading to the dorsum of the feet, or as a non-localised, non-pitting edema of the skin in the same areas. In advanced cases, this may extend to the upper trunk (torso), upper extremities, face, neck, back, chest and ears.

The lesions are known to resolve very slowly. Application of petroleum jelly on the affected area could relieve the burning sensation and the itching. It occasionally occurs in non-thyrotoxic Graves' disease, Hashimoto's thyroiditis, and stasis dermatitis. The serum contains circulating factors which stimulate fibroblasts to increase synthesis of glycosaminoglycans.

Acroangiodermatitis of Mali (also known as "Mali acroangiodermatitis" and "Pseudo-Kaposi's sarcoma") is a rare cutaneous condition often characterized by purplish-blue to brown papules and plaques on the medial and lateral malleolus of both legs.

Acroangiodermatitis is a rare skin condition characterised by hyperplasia of pre-existing vasculature due to venous hypertension from severe chronic venous stasis. It is associated with amputees, haemodialysis (HD) patients with arteriovenous (AV) shunts, and patients with paralysed legs, hepatitis C, chronic venous insufficiency or AV malformations (AVM). Patients present with itchy, painful, confluent, violaceous or brown-black macules, papules or plaques usually at the distal lower limbs. There may be ulceration and bleeding. The histologic features are capillary proliferation and perivascular inflammation involving eosinophils in the dermis with minimal epidermal changes. Management includes compression therapy, wound care and surgical correction of AVM. Dapsone combined with leg elevation and compression, and erythromycin for HD patients with AV fistulas have also been reported. The lesions may persist for years with complications like ulceration, bleeding and infection.

Pretibial myxedema (myxoedema (UK), also known as Graves' dermopathy, thyroid dermopathy, Jadassohn-Dösseker disease or Myxoedema tuberosum) is an infiltrative , resulting as a rare complication of Graves' disease, with an incidence rate of about 1-5% in patients.

Multifocal lymphangioendotheliomatosis (also known as "Congenital cutaneovisceral angiomatosis with thrombocytopenia," and "Multifocal Lymphangioendotheliomatosis with thrombocytopenia") presents at birth with hundreds of red-brown plaques as large as several centimeters.

PVS sufferers often complain of a burning sensation with the tongue and oral mucosa, and atrophy of lingual papillae produces a smooth, shiny, red, dorsum of the tongue. Symptoms include:

Serial contrasted gastrointestinal radiography or upper gastrointestinal endoscopy may reveal the web in the esophagus. Blood tests show a hypochromic microcytic anemia that is consistent with an iron-deficiency anemia. Biopsy of involved mucosa typically reveals epithelial atrophy (shrinking) and varying amounts of submucosal chronic inflammation. Epithelial atypia or dysplasia may be present.It may also present as a post-cricoid malignancy which can be detected by loss of laryngeal crepitus. Laryngeal crepitus is found normally and is produced because the cricoid cartilage rubs against the vertebrae.

Papular mucinosis is chronic and may be progressive. The dermal layer of the skin breaks out into small and solid bumps, usually conical in shape and measured from 2 to 4 mm or sometimes flat-topped papules. Unlike pustules, these bumps do not contain pus. Instead they contain mucin, a substance of mucus, the body's natural and protective lubricant found in saliva and epithelial cells in lungs and the sensitive part of the nose. They usually come in clusters such as linear arrays. Less frequently, urticarial, nodular, or sometimes annular lesions may be appreciated. The dorsal aspect of the hands, face, elbows, and extensor portions of the extremities are most frequently affected. Mucosal lesions are absent. The coalescence of papules on the face, particularly on the glabella, results in longitudinal folding and gives the appearance of a leonine facies.

In scleromyxedema, symptoms can occur on larger part of the body. Erythema and scleroderma-like induration occurs on the skin. In addition, the mobility of the lips, hands, arms, and legs is reduced. Proximal myopathy, inflammatory polyarthritis, central nervous system symptoms, esophageal aperistalsis, and hoarseness are among the notable systemic symptoms. If viscera is involved, the disease will be fatal. The dermatoneuro syndrome is a rare neurological complication of the disease presenting with fever, seizures and altered mental status.

Plummer–Vinson syndrome (PVS), also called Paterson–Brown–Kelly syndrome or sideropenic dysphagia, is a rare disease characterized by difficulty in swallowing, iron deficiency anemia, glossitis, cheilosis and esophageal webs. Treatment with iron supplementation and mechanical widening of the esophagus generally provides an excellent outcome.

While exact data about the epidemiology is unknown, this syndrome has become extremely rare. The reduction in the prevalence of PVS has been hypothesized to be the result of improvements in nutritional status and availability in countries where the syndrome was previously described. It generally occurs in postmenopausal women. Its identification and follow-up is considered relevant due to increased risk of squamous cell carcinomas of the esophagus and pharynx.

Some clinical examples:

Other examples are:

- Subacute bacterial endocarditis

- Symptoms of malaria

Xanthoma disseminatum (also known as "Disseminated xanthosiderohistiocytosis" and "Montgomery syndrome") is a rare cutaneous condition that preferentially affects males in childhood, characterized by the insidious onset of small, yellow-red to brown papules and nodules that are discrete and disseminated.

It is a histiocytosis syndrome.

Pseudoporphyria is clinically characterized by increased skin fragility; erythema; and the appearance of tense bullae and erosions on sun-exposed skin, which are identical to those seen in patients with PCT. However, a clinical pearl that may prove helpful in differentiating between pseudoporphyria and PCT is that the classic features of hypertrichosis, hyperpigmentation, and sclerodermoid changes found with PCT are unusual with pseudoporphyria.

A second clinical pattern of pseudoporphyria has a similar presentation to erythropoietic protoporphyria (EPP), an autosomal dominant porphyria resulting from a reduced activity of ferrochelatase.

In contrast to PCT, EPP usually begins in childhood with a history of photosensitivity, often described as a burning sensation immediately after sunlight exposure.

Clinically, EPP is characterized by erythema, edema, shallow scars, and waxy induration of the skin, particularly on the face.

Pseudoporphyria that clinically mimics EPP has been described almost exclusively in children taking naproxen for juvenile rheumatoid arthritis. Naproxen-induced pseudoporphyria seems to have a dimorphic presentation with the PCT-like pattern more often seen in the adult population and the EPP-like pattern more commonly seen in children, although some overlap has been documented.

Idiopathic eruptive macular pigmentation is a skin condition developing in young persons, with an average age of 11, characterized by asymptomatic widespread brown to gray macules of up to several centimeters in diameter on the neck, trunk, and proximal extremities.

Findings of tenderness, induration, pain and/or erythema along the course of a superficial vein usually establish a clinical diagnosis, especially in patients with known risk factors. In addition, there is often a palpable, sometimes nodular cord, due to thrombus within the affected vein. Persistence of this cord when the extremity is raised suggests the presence of thrombus.

Papular mucinosis (also known as "Scleromyxedema," "Generalized lichen myxedematosus," and "Sclerodermoid lichen myxedematosus") is a rare skin disease. Localized and disseminated cases are called papular mucinosis or lichen myxedematosus while generalized, confluent papular forms with sclerosis are called scleromyxedema. Frequently, all three forms are regarded as papular mucinosis. However, some authors restrict it to only mild cases. Another form, acral persistent papular mucinosis is regarded as a separate entity.

The cause is unknown; however it is thought to be associated with sun exposure, leading to a dilated blood-filled vascular channel "...lined with a singled layer of flattened endothelial cells and a thin wall of fibrous tissue filled with red blood cells."