Cytologic diagnosis of mastocytosis by fine needle aspiration biopsy: a case report.

BACKGROUND

Mastocytosis is an abnormal proliferation of mast cells and their subsequent accumulation in various organs. Diagnosis of mast cell disease relies on proper identification of abnormal mast cells.

METHODS

A 55-year-old man presented with a history of fever for several months, associated with night sweats, involuntary 20lb weight loss, progressive fatigue, weakness, worsening abdominal distention, shortness of breath, and diffuse lymphadenopathy. Physical examination and computed tomography (CT) showed hepatosplenomegaly, massive ascites, and generalized lymphadenopathy. Bone marrow biopsy with immunohistochemistry (ICH) studies revealed mastocytosis. CT-guided fine needle aspiration biopsy (FNAB) of the retroperitoneal lymphadenopathy was performed. The smears were cellular for a mixed population of mature plasma cells, eosinophils, left-shifted granular and lymphoid cells, and abundant abnormal mast cells. The mast cells had round to oval lobulated nuclei, some of which were binucleated or eccentrically located, with coarse, evenly distributed chromatin. Abundant pale cytoplasm contained numerous metachromatic granules. IHC studies and flow cytometry confirmed the cytologic diagnosis of mastocytosis.

CONCLUSIONS

This case highlights the cytologic features of mastocytosis in FNA specimens. IHC stains and flow cytometry are helpful to confirm the cytologic diagnosis. To the best of our knowledge, this is the second case that describes the cytologic characteristics of mastocytosis.