A Hematologic Mimic: Sarcoidosis Presenting With Myelodysplastic Syndrome-Like Marrow Dysplasia, Massive Splenomegaly, and Pancytopenia.

Sarcoidosis is a multisystem granulomatous disorder of unknown etiology with heterogeneous clinical manifestations and significant diagnostic challenges, particularly when extrapulmonary involvement predominates. Although splenic, hematologic, metabolic, and lymphatic manifestations are individually recognized, their simultaneous occurrence is exceptionally rare. We report a diagnostically complex case of sarcoidosis presenting with massive splenomegaly, pancytopenia, parathyroid hormone-independent hypercalcemia with renal dysfunction, and bone marrow findings suggestive of myelodysplastic syndrome. A 53-year-old man was incidentally found to have pancytopenia during routine evaluation and was asymptomatic at presentation, without constitutional symptoms. Abdominal imaging revealed massive splenomegaly with preserved hepatic morphology. Bone marrow aspiration and biopsy demonstrated multilineage dysplasia with low blast percentage, favoring myelodysplastic neoplasia; however, this diagnosis was discordant with the presence of massive splenomegaly. Subsequent biochemical evaluation revealed hypercalcemia with suppressed parathyroid hormone levels and associated renal dysfunction, prompting further investigation.