Proteinaceous Lymphadenopathy Masquerading as Malignancy: a Rare Case Presenting a Diagnostic Dilemma.

Proteinaceous lymphadenopathy (PLD) is a rare poorly defined, underrecognized entity of uncertain etiology, characterized by massive deposition of amorphous, acellular, eosinophilic, PAS-positive material within an enlarged lymph node. We report an unusual case of a 46-year-old female with a large abdominal lump in the left lumbar region with inguinal lymphadenopathy. Contrast-enhanced computed tomography (CECT) showed multiple variable-sized lobulated non-enhancing soft tissue attenuated masses showing multiple peripheral and central calcific foci in the right para-aortic, bilateral iliac region, pelvis on the left side and left inguinal region. No evidence of any abnormal hypermetabolic focus was found in the neck, chest, abdomen, and pelvis on fluorodeoxyglucose positron emission tomography. A large, well-defined, non-FDG avid mass lesion with significant central and peripheral calcification in the left iliac fossa, abutting the descending colon, was seen. A biopsy of left-sided inguinal lymph nodes revealed large masses of an amorphous, acellular, eosinophilic material with areas of mature lymphoid cell aggregates interspersed between the pink amorphous materials. A final impression of proteinaceous lymphadenopathy was given. Proteinaceous lymphadenopathy is a benign condition with often a large mass masquerading as malignancy. It is a major therapeutic challenge for pathologists and clinicians. Histopathologists need to be vigilant in such cases and be aware of the morphological appearances in such cases.