[Congenital histiocytoma: a benign disease]

We report on a newborn presenting a solitary congenital skin nodule due to Langerhans cell histiocytosis. This benign lesion is rare and has been described in the literature under a variety of names; there is no consensus regarding treatment.

A 28-day-old newborn presented with a solitary congenital blue-brown nodule measuring 1cm on the left iliac fossa. Histological examination of a skin biopsy showed a proliferation of histiocytes throughout the dermis with an immunohistochemical profile of Langerhans cells. The lesion resolved spontaneously, with rapid reduction of the infiltration, and at 16 weeks only a pigmented scar remained.

Thirty-eight similar cases have been reported in the literature under a variety of different names. The lesions noted consisted of a solitary brownish nodule measuring 1cm which was congenital in almost all cases, often ulcerated and exhibited no predilection for any particular body site. Histological examination revealed dermal proliferation of Langerhans cells. Electronic microscopy revealed dense intracytoplasmic bodies and Birbeck's granules. Laboratory and radiological tests did not show systemic involvement in any cases. All lesions other than those surgically removed regressed spontaneously within a mean 8 weeks. It appears necessary to differentiate between congenital and other forms of histiocytoma since therapeutic strategies differ. Spontaneous resolution of lesions and lack of systemic involvement militate in favour of simple clinical follow-up, with surgical excision and further tests required only for cases lasting 6 months and beyond.