Clinical features of familial histiocytosis.

: The most commonly reported familial variant of histiocytosis is familial hemophagocytic lymphohistiocytosis. Clinically, this may be distinguished from other infantile forms by the absence of skin involvement and high incidence of leptomeningeal involvement. Eosinophilia, erythematous skin rash, alopecia, and opportunistic pulmonary infections suggest combined immunodeficiency with histiocytic response.