HEREDITARY PROGRESSIVE MUCINOUS HISTIOCYTOSIS

We describe hereditary progressive mucinous histiocytosis, a rare auto somal dominant non-Langerhans cell histiocytosis, in a mother and daug hter. Both had similar, progressive eruptions of skin-colored to red-b rown papules on the nose, hands, forearms, and thighs. Light microscop y showed small collections of epithelioid histiocytes and telangiectat ic vessels in the upper dermis of early lesions. In the mid dermis of early and well-developed lesions, nodular aggregates of tightly packed spindle-shaped cells were seen. Moderate to extensive mucin productio n was demonstrated in epithelioid histiocytes and spindle-shaped cells . Electron microscopy of spindle-shaped cells revealed many dendritic histiocytes with abundant lysosomal storage organelles such as myelin bodies and zebra bodies. Immunohistochemistry showed expression of mac rophage antigens (CD68; MS-1 high-molecular-weight protein) in epithel ioid histiocytes and in some of the spindle-shaped cells. The histolog ic and immunohistochemical features of hereditary progressive mucinous histiocytosis most closely resemble solitary histiocytoma/cellular-ty pe dermatofibroma.