Transformation of monocytoid B-cell lymphoma to large cell lymphoma associated with crystal-storing histiocytes

We report a case of crystal-storing histiocytosis associated with large cel l lymphoma in a patient with a history of monocytoid B-cell lymphoma 10 yea rs previously The cervical lymph node biopsy showed a diffuse proliferation of large lymphocytes with vesicular nuclear chromatin and distinct nucleol i. These lymphocytes were associated with numerous immunoglobulin lambda li ght-chain crystal-storing histiocytes, which morphologically resembled rhab domyoblasts. Occasional lymphoid cells also showed large immunoglobulin cry stals. This case establishes the association of crystal-storing histiocytes with lymphomas of mucosa-associated lymphoid tissue and emphasizes the nee d for immunophenotyping to distinguish these unusual cases from other tumor s, particularly adult rhabdomyomas.