[Acquired atrophic pigmented band-like lesions following Blaschko's lines]. / Bandes pigmentées atrophiques acquises suivant les lignes de Blaschko.

Over a seventeen years period we observed 5 patients presenting with very similar lesions the equivalent of which we could not find in the literature. These were pigmented and more or less atrophic bands which exactly followed Blaschko's lines. The lesions appeared during childhood or adolescence, between the ages of 6 and 20 years and always were unilateral. In all cases they were located on the trunk where they formed a recumbent "S" pattern characteristic of Blaschko's lines. They often started 3 to 6 cm away from the posterior midline and ended precisely on the anterior midline. These bands varied in number and in 3 out of 5 cases they were associated with pigmented atrophic bands or lines on the limbs of the same side. The intensity of pigmentation and atrophy was variable. The lesions were asymptomatic and only caused a cosmetic prejudice. They were perfectly fixed, and during a 2 to 30 years observation period they remained unmodified. The five skin biopsies performed on 3 patients showed no abnormality of the epidermis other than irregular and moderate hyperpigmentation of its deep part. In the dermis, there was no distinct pigment incontinence, no inflammation and no alteration of connective tissue texture; the elastic network was invariably normal. The impression of skin atrophy was not due to true dermal hypoplasia and perhaps corresponded to atrophy of the subcutaneous cellular tissue. No biological disturbance was observed. These lesions can easily be distinguished from epidermic naevi, incontinentia pigmenti and areas of hypoplastic dermis.(ABSTRACT TRUNCATED AT 250 WORDS)

[Epidermal cyst and osteolysis of the cranial vault]. / Kyste épidermique et ostéolyse de la voûte crânienne.

In a 40-year old man undergoing, under local anaesthesia, excision of an epidermal cyst located in the frontal region, at the border of the scalp, the operator had difficulties in removing the deep part of the cyst and perceived an underlying bone depression. The depression was caused by a 2 x 1.3 cm wide lacuna in the calvarium, which was subsequently treated by neurosurgeons. Histology showed only fragments of a simple epidermal cyst wall and no evidence of dermoid cyst. The causes of osteolysis associated with congenital or acquired skin lesions are reviewed. In this case, the old age and volume of the cyst may explain the osteolysis by mechanical compression. This case is exceptional since we were unable to find other examples in the literature, apart from dermoid and trichilemmal cysts.