engleski

Mast cell sarcoma of tibia

Mastocytosis is a rare and mainly sporadic disease. Its main feature is an abnormal proliferation and tissue accumulation of mast cells. Mast cell sarcoma is a very rare disease, with 3 well-documented cases described in literature. It is characterized by local proliferation of atypical mast cells, destructive growth and very poor prognosis. A 4-year-old boy, presented with painful edema and deformation of his right lower leg. X-rays and CT revealed destructive tumorous mass. Histopathology showed tumour very rich with large, atypical cells, with hyperchromatic oval and polygonal nuclei. Cytoplasm around them was eosinophilic with many PAS-positive and Toluidine-Blue-positive granules. Immunohistochemically mast cells were positive for CD68, vimentin, CD 117 and CD 45. Soon rush developed with elevated serum tryptase level. One month after biopsy, disease progressed to mast cell leukemia. Follow-up computed tomography showed oval masses in both lower limbs. Targeted biopsy of the right tibia showed same pathohistological findings as the first one. Despite intensive chemotherapy patient died 8 months after first symptoms. Based on pathological findings, histochemistry and immunohistochemistry, we diagnosed for the first time a mast cell sarcoma of a bone, leading to leukemic transformation and death.

mast cell sarcoma; bone tumor; mast cells; c-kit; mast cell leukemia

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