Neuroblastoma (NB) is the most common extra-cranial cancer of early childhood and rarely occurs in adults. The clinical symptoms of NB can be diverse. We discuss a rare case of an adult NB presenting as acute leukemia. A 45-year-old woman presented with persistent hip pain, weight loss, anemia, and incidental fever for several months. Imaging studies showed diffuse bone marrow (BM) uptake and hypermetabolic lesions involving the left adrenal gland, bilateral axillary nodes, and left lateral aspect of the abdomen. Her 24-hour urine catecholamines were within the normal range. On the peripheral blood film, blast-like cells were noted, occupying approximately 2% of leukocytes. The BM imprints showed infiltration of blast-like cells with convoluted nuclei and scant cytoplasm in more than 85% of the total nucleated cells. Acute leukemia was initially suspected based on morphology. Blast-like cells were negative for myeloperoxidase, combined esterase, periodic acid-Schiff, CD45RB, CD68, and CD138. In a further study, these cells were positive for CD56, synaptophysin (SYN), and CD99 with negativity for desmin, myogenin, NKX-2.2, CD31, cytokeratin (AE1/AE3), Melan-A, ERG, S-100, and SALL4. Morphologically similar neoplastic cells in axillary node biopsy were positive for CD56, chromogranin A, SYN, and neurofilament, but negative for GFAP, CD246, and vimentin. Based on laboratory, pathological, and imaging studies, metastatic NB with BM and multifocal involvement was diagnosed. The differential diagnosis of metastatic small blue round cell tumors should be considered for adult patients with circulating blast-like cells, and an accurate diagnosis would enable the patient to receive appropriate and timely treatment.
Keywords: cytomorphology; differential diagnosis; immunohistochemistry; neuroblastoma; small blue round cell tumor.
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