Melanotic spots of the mucous membranes L81.4

Acquired hyperpigmentation of the genital (lentigo of the glans penis, lentigo of the vulva), anal or oral mucous membranes, which can occur both in the female and male sex.

The melanotic (melanocytic) patches of the mucosa, occurring in singular or in small majority, are usually harmless, and on the one hand may appear as physiological pigmentation. They are observed more frequently in dark-skinned people than in light-skinned people.

On the other hand, they can also appear as true melanocytic neoplasms (lentigo) and then require clinical control.

However, lentiginosis of the mucous membranes can also be an indication of a genodermatosis (see lentiginosis below) and occur, for example, in connection with LAMB, Peutz-Jeghers, Laugier-Hunziker or Cowden syndromes . In connection with the last two syndromes, it should be noted that lentigines of the penis may indicate a mutation in the tumor suppressor gene PTEN (phophatase and tensin homolog, deleted on chromosome 10).

Clinical differential diagnosis of lentiginous mucosal pigmentation:

• Hereditary:
  • Laugier-Hunziker syndrome
  • Peutz-Jeghers syndrome
  • NAME syndrome
  • Neurofibromatosis
  • Albright syndrome
  • Incontinentia pigmenti.
• Melanocytic neoplasms and malformations (hamartomas):
  • Lentigo simplex (melanotic spot of the mucosa)
  • Junction typemelanocytic nevus
  • Lentigo maligna
  • Mucosal melanoma
  • Blue nevus
• Other circumscribed hyperpigmentation:
  • Idiopathic (mostly solitary) hyperpigmentation
  • Ethnic-induced hyperpigmentation (skin types 5-6)
  • Drug-induced(tetracyclines, chloroquine, sedatives, anticonceptives).
  • Postinflammatory pigmentation ( lichen planus; fixed drug reaction)
  • Smoker's melanosis (see below Leukokeratosis nicotinica palati)
  • Amalgam tattooing (after dental surgery)
  • Decorative pigmentation
  • Heavy metal fringes ( lead pigmentation of the oral mucosa; stomatitis bismutica).

No sex preference; rarely congenital, usually acquired between 20 and 60 LY.

Lips (especially lower lip), oral mucosa, vulva, vagina, penis, anus.

Mostly solitary, rarely multiple, mostly jagged, irregularly limited, rarely rounded, also large brown or brown-black spot(s).

Picture of lentigo simplex with basal hyperpigmentation and increase (!) of melanocytes. Often dendritic melanocytes are detectable. Subepithelial mostly clumpy pigment in melanophages.

Clinical:

• See below classification; important is the differentiation to a mucosal melanoma. The latter is usually darker, sharply demarcated and always solitary.

Histological:

• amalgam tattoos: evidence of metal deposits
• Melanoacanthoma of the mucosa: found mainly in women of colour.
• Melanoma in situ: disorderly proliferation of atypical melanocytes.
• Lichen planus mucosae: in the healing phase, lichen planus mucosae may be accompanied by a scaly postinflammatory hyperpimgentation

With regard to the nomenclature of melanosis, chloasma and lentigo or lentiginosis, see below. melanosis.

1. Cengiz FP et al (2015) Dermoscopic and clinical features of pigmented skin lesions of the genital area. An Bras Dermatol 90:178-183.
2. Delaney TA et al (1994) Penile melanosis successfully treated with the Q-switched ruby laser. Br J Dermatol 130: 663-664
3. Hwang L et al (2000) Off-center fold: irregular, pigmented genital macules. Arch Dermatol 136: 1559-1564
4. Isbary G et al (2014) Penile lentigo (genital mucosal macule) following annular lichen planus: a possible association? Australas J Dermatol 55:159-161
5. Kanj LF et al (1992) Vulvar melanosis and lentiginosis: A case report. J Am Acad Dermatol 27: 777-778
6. Revuz J et al (1989) Penile melanosis. J Am Acad Dermatol 20: 567-570
7. Stratigos AJ et al (2003) Lasers and aesthetic dermatology. Dermatologist 54: 603-613