Plasma Cell Neoplasm with Clear Cell Morphology—A Diagnostic Dilemma

Abstract

Apart from their usual morphology (eccentrically placed round to ovoid nuclei with cart-wheel-like chromatin, perinuclear halo and deep basophilic cytoplasm), very rarely plasma cells show varied appearances—signet-ring, pleomorphic, blastic, vacuolated, spindle cell, and clear cell.1 Here, we present a case of plasmacytoma involving the right pleural cavity with unusual morphology and masquerading as a nonhematolymphoid neoplasm. A 75-year-oldwomanpresentedwith complaints of weakness, shoulder, and back pain with breathlessness. Magnetic resonance imaging (MRI) of the thoracic spine (►Fig. 1A) showed a heterogeneous lesion measuring 11.3 2.5 3.9 cm in the right pleural cavity with involvement of the adjacent ribs, costovertebral joints, and infiltration of the right neural foramina in the T3 toT4 and T4 toT5 regions. The lesion showed low fluorodeoxyglucose (FDG) uptake on positron emission tomography-computed tomography (PET-CT) scan with standardized uptake value (SUV) max of 3.3. Needle core biopsy of the lesion under ultrasound guidance was done. Histopathological examination revealed fibrocollagenous tissue and skeletal muscle bundles with neoplastic cells arranged in cords and sheets (►Fig. 1B). The