Unusual hand nodules

These hands show crystal storing histiocytosis in a woman in her 705 (fig 1). The firm nodules, which had been presentfor 13 years, were only occasionally tender and inflamed. Previous needle aspiration biopsy samples had been devoid ofurate crystals but showed inflammatory cells without a specific diagnosis. The patient had rheumatoid arthritis and monoclonal gammopathy of undetermined significance (MGUS) for 23 and 20 years ago, respectively. Such hand nodules are typically associated with rheumatoid arthritis, but this patient was seronegative forthe disease. Histology showed a subdermal necrotic mass with
neutrophils surrounding crystal-like hyaline bodies; staining with periodic acid Schiff was positive and staining with Congo red was negative. This was consistent with crystal storing histiocytosis associated with the patient’s MGUS. Crystal storing histiocytosis is a rare manifestation ofMGUS, multiple myeloma,
and some types of lymphoma that can affect the kidneys, lungs, bone marrow, lymph nodes, liver, spleen, and gastrointestinal tract.