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We report two atypical cases of membranous aplasia cutis surrounded by a rim of hairs, one case associated with dense dermal melanocytosis and the other with naevus flammeus, with characteristic clinical features. A rim of hypertrichosis, 'hair collar' sign, is proposed to have a close association with neuroectodermal defects. A failure of the normal closure of the cranial neural tube might have affected foetal skin development, including melanoblast migration and capillary network formation. The changes in the present cases, as well as the hair collar sign may suggest a complex hamartomatous nature of membranous aplasia cutis.

Becker's melanosis is a distinct clinical entity. It usually presents in adolescence as a unilateral, hyperpigmented, hairy cutaneous hamartoma. We report herein 12 cases of Becker's melanosis that differ in their presentation from classical Becker's melanosis, and we believe that such presentations are not uncommon.

We report a 4-year-old Caucasian girl with congenital skin lesions consisting of hyperpigmented macules that were bilateral and roughly symmetrical, covered with terminal hair and located on the scapular regions, shoulders, and arms. A cutaneous biopsy specimen showed the histologic pattern of Becker nevus. We discuss the classification of this case in the context of the published literature.

Becker's melanosis is an uncommon condition characterized by hypertrichosis, hyperpigmentation of the epidermis, dermal melanophages and absence of nevus cells. Ultrastructural examination of such a melanotic lesion from a young white man revealed giant melanosomes. In addition, normal-sized melanosomes were found singly in the keratinocytes of the involved skin. Dermal venules were surrounded by multiple layers of basement membrane.

The case of a 10 year-old Japanese boy with erythrokeratodermia variabilis is reported in addition to a review of the Japanese literature. The patient was first examined in our clinic on October 21, 1965, because of generalized hyperkeratotic lesions and erythematous lesions which had persisted since he was 3 months old. Hyperkeratotic and verrucous lesions were noted on his auricles and trunk, on which there were also sharply demarcated erythematous lesions of various sizes and shapes which were not elevated from the adjacent skin. Laboratory findings were within normal limits. Histopathological examination revealed a remarkable hyperkeratosis with a basket weave appearance, moderate acanthosis and a slightly thickened granular layer. Polyethylenglycol 400 and corticosteroid ointment were slightly beneficial to the hyperkeratotic lesions.

A healthy 14-year-old Norwegian male developed a typical Becker's naevus on the left shoulder and upper scapular region, about six months after an intracutaneous BCG-vaccination in the homolateral junction of the shoulder and upper arm. The evolution of the lesion had been modified by exposure to sunlight during the following six years, with partial fading of the hyperpigmentation. Biopsies taken from the centre and from the edge of the lesion at the age of 19 years showed the usual histological picture seen in cases of Becker's naevus, but focal areas within the periphery showed a chronic granulomatous infiltrate of lupoid pattern in the dermis, mainly follicular and perifollicular in distribution. Acid-fast bacilli were not demonstrable in the sections, and in culture no tubercle bacilli were isolated from a central and histologically non-specific site. The implications of the histological findings are discussed, stressing the possibility that Becker's naevus may be a form of cutaneous tuberculosis caused by BCG or other mycobacteria of low virulence, precipitated by ultraviolet light and possibly modified by immunological factors.

Histological investigations were performed in 11 subjects suffering from melanosis naeviformis Becker. Apart from the well-known epidermal alterations such as basal hyperpigmentation, slight acanthosis and growth of coarse hair, dermal changes were found in each case. The dermis was considerably thickened and contained numerous small and/or large bundles of smooth muscle without relation to cutaneous adnexa. Thus, melanosis naeviformis Becker can be considered an organoid nevus with epidermal, melanocytic and dermal components.