Case 395

Submitting Author: Metcalf, Ryan Adams, MD
Institution: Stanford University Medical Center
Additional authors:Yaso Natkunam MD, PhD
Session: Extramedullary manifestations of myeloid neoplasms

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HISTORY

1-year-old Mayan female with fever, weight loss, and abdominal distension without splenomegaly or peripheral lymphadenopathy. Case received in consultation from Guatemala.

DETAILS

Formalin-fixed retroperitoneal mass. Microscopic findings: Sheets and nests of intermediate-sized cells with round nuclei, immature chromatin, and scant to moderate amounts of faintly eosinophilic cytoplasm. Numerous mitotic figures and areas with karyorrhectic debris are identified, with some areas showing a “starry sky” appearance.

IMMUNOHISTOCHEMISTRY AND FLOW CYTOMETRY

Positive: Glycophorin C, CD43 (subset), CD38 (weak), INI intact.

Negative: Cytokeratin, synaptophysin, NB84, WT1, desmin, myogenin, CD99, S100, SALL4, CD45, CD34, CD117, MPO, CD10, TdT, CD3, CD4, CD79a, CD20, bcl-2, CD30, ALK, EBV RNA, CD61, CD68, CD123, and CD138.

CYTOGENETIC FINDINGS

Not performed.

MOLECULAR FINDINGS

Not performed.

INTERESTING FEATURES

• Distinct erythroid differentiation demonstrated by positive glycophorin C immunostaining
• Differential diagnostic overlap with Burkitt lymphoma
• CD43 (subset positive) and CD38 (weakly positive) are only other positive markers of differentiation

PROPOSED DIAGNOSIS

Myeloid sarcoma with erythroid differentiation

CONSENSUS GROUP: ADDITIONAL INFORMATION/STUDIES

Additional immunohistochemical stains performed by the consensus group:

E-cadherin: negative
CD43: positive

CONSENSUS DIAGNOSIS

Myeloid sarcoma (erythroid differentiation) involving retroperitoneum