SUMMARY Identical twin sisters are described who developed lupus erythematosus associated with erythema multiforme‐like lesions.

Dermal hypoplasia is reported in three patients with neurofibromatosis. The areas of dermal hypoplasia failed to react to vasodilator stimuli and responded poorly to a vasoconstrictor stimulus. Histology of these lesions showed neurofibromatous tissue and at an ultrastructural level cells resembling perineurial cells were wrapped around dermal vessels. The poor vascular responses seen in these areas of neurofibromatous dermal hypoplasia might be due to the perineurial cells acting as a barrier to diffusion of the pharmacological agents and as a physical perivascular splint.

A young man with a 4-year history of lymphomatoid papulosis subsequently developed a systemic lymphoma. Further doubt is therefore cast on the benign nature of this disorder.

Summary A case of histiocytosis X is reported in which the presenting feature was recurrent cutaneous ulceration indistiguishable from pyoderma gangrenosum. Such a presentation of histiocytosis X has not previously been described.

No abstract