[Multicentric reticulohistiocytosis and myelodysplastic syndrome]

Multicentric reticulohistiocytosis: a proliferation of macrophages with tropism for skin and joints, part II

In this second part of the review of multicentric reticulohistiocytosis, the authors discuss its association with other diseases, in particular, cancer, and laboratory and therapeutic aspects of this incapacitating and disfiguring disease. Histopathologic aspects are characteristic: dense mononuclear infiltrate with typical multinucleated cells that contain periodic acid-Schiff-positive and diastasis-resistant material, conferring a "ground glass" aspect when stained with hematoxylineosin.

Multicentric reticulohistiocytosis

BACKGROUND

Multicentric reticulohistiocytosis (MR) is a rare histiocytic systemic disease mainly affecting the skin and synovia.

OBJECTIVE

To present the main and newest aspects of MR.

METHOD

A review of the current medical literature, composing a retrospective study of 96 case reports published world-wide since 1977.

RESULTS

Facial and hand skin nodules with symmetric arthritis were the most frequent clinical presentation. The pathognomonic sign of'coral beads' and vermicular erythematous lesions bordering nostrils, seems to be very characteristic of MR. There is a significant association with cancer. Histiocytic cells of MR are best characterized on immunohistochemistry by its immunoreactivity for vimentin, CD68 and CD45 and non-reactivity for S-100 protein, CD34 and factor XIIIa. Although the outcome of the disease is usually very limiting for the patients, treatment with immunosuppressive drugs may be useful.

CONCLUSION

MR is a unique histiocytic proliferative disease with a peculiar immunophenotypic pattern and distinctive clinical and histopathological aspects.

Hereditary progressive mucinous histiocytosis

We describe hereditary progressive mucinous histiocytosis, a rare autosomal dominant non-Langerhans cell histiocytosis, in a mother and daughter. Both had similar, progressive eruptions of skin-colored to red-brown papules on the nose, hands, forearms, and thighs. Light microscopy showed small collections of epithelioid histiocytes and telangiectatic 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 production 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 macrophage antigens (CD68; MS-1 high-molecular-weight protein) in epithelioid histiocytes and in some of the spindle-shaped cells. The histologic and immunohistochemical features of hereditary progressive mucinous histiocytosis most closely resemble solitary histiocytoma/cellular-type dermatofibroma.