Focal acral hyperkeratosis is a disorder characterized by hyperkeratotic papules along the border of the hands and feet. Focal acral hyperkeratosis and several marginal punctate keratodermas closely resemble acrokeratoelastoidosis of Costa. The question if there is a difference between acrokeratoelastoidosis of Costa and focal acral hyperkeratosis or if they are variants of the same entity are discussed. We report a case showing focal acral hyperkeratosis, review the clinical and histological features of related conditions and present a modified concept of marginal papular acrokeratodermas.

Sinus histiocytosis is as a rule a benign disease of lymph nodes, infiltrated by large histiocytes. These cells show typical cytophagocytosis, particularly lymphophagocytosis. Other organs may be also involved by this disease, often including the skin. Exclusive cutaneous sinus histiocytosis without infiltration of lymph nodes seems to be very rare. To exclude other non-X histiocytoses or histiocytosis-X, it is advisable to use immunohistochemistry. We report on a patient with sinus histiocytosis and discuss the problems of differential diagnosis.