Melanosis L81.4

Neither in the dermatological nor in the non-dermatological linguistic usage uniformly used terminology (see below note). In general dermatological usage, this is understood to mean congenital or acquired, localized or disseminated, solitary or generalized or also universal, pathological dark discoloration of the skin and/or mucous membrane ( hyperpigmentation in the narrower sense), caused by increased deposits of melanin in the epidermis/mucosa and/or dermis/tunica propria.

S.a. Dyschromia.

Hypomelanosis (better known as hypopigmentation) is a lack of pigment, which can be caused by a lack of melanin or a lack of melanocytes.

"Hypermelanosis" (better: hyperpigmentation) is therefore caused either by numerical increase of melanocytes (example: lentigo simplex) or by increase and increased transfer of melanin (example: ephelides) or by the combinations. Hyperpigmentations are also caused by accumulation of melanin in the dermis (blue colour). Melanin can occur freely in the dermis or bound in melanophages (e.g. through pigment incontinence) or in dermal melanocytes (e.g. in the blue nevus).

Basically, one can distinguish between localized and generalized melanoses as well as between melanoses of the mucous membranes and the skin.:

Melanosis of the mucosa (melanocytic pigmentation).

Melanosis of the skin ( hyperpigmentation in the narrower sense).

• Generalized melanosis occurs in the following underlying diseases/causes:
  • Antibiotic therapy (tetracyclines).
  • Addison's disease
  • Arsenic intoxications
  • Graves' disease
  • Cushing's syndrome
  • Hepatolenticular degeneration (Wilson's disease)
  • Dyschromatosis universalis hereditaria
  • Fanconi syndrome
  • Carcinoid syndrome
  • Metastatic malignant melanoma
  • Melanodermatitis toxica
  • Melanoerythroderma
  • Melanosis diffusa congenita
  • Nelson syndrome
  • Cirrhosis, biliary (see below liver diseases, skin lesions)
  • Acanthosis nigricans (hyperpigmentation and areal acanthosis)
  • Acropigmentation (so-called lace pigmentation)
  • Acropigmentation (symmetrical)
  • Pregnancy
  • Melanosis perioralis et peribuccalis
  • Renal insufficiency, chronic terminal
  • Pellagra
  • Multiple endocrine neoplasia (perianal hyperpigmentation in familial colonic polyposis)
  • Porphyria cutanea tarda
  • Systemic scleroderma
  • Circumscribed scleroderma
  • Riehl's melanosis
  • Chloasma hepaticum (biliary cirrhosis)
  • Cytostatic therapy (e.g. bleomycin, melanodermia factitia)
  • Transitory neonatal pustular melanosis.
• Localized melanoses
  • Circumscribed hyperpigmentation (melanosis), including that of the mucosa, are included under the terms of lentigo simplex, lentigo solaris, melasma, and others. The term "melanotic spot of the mucosa" is just as dispensable as the term "genital melanosis" (see below Melanosis , genital) or mucosal melanosis.
  • Also the circumscribed hyperpigmentation in peripheral neurofibromatosis or in Pringle's phakomatosis are not called melanoses but café au lait spots. Histologically, they correspond to lentigo simplex.

The term melanosis is also used in other fields, again in different interpretations (e.g. melanosis of the colon; melanosis of the conjunctiva).

1. Giehl K et al (2010) Genetically caused pigmentation disorders. Dermatologist 61: 567-577