Myeloid sarcoma: A clinicopathological study with emphasis on diagnostic difficulties

Area of Science:

• Oncology
• Hematopathology
• Diagnostic Pathology

Background:

• Myeloid sarcoma (MS) is a rare extramedullary tumor of myeloid precursors, often associated with acute myeloid leukemia.
• MS can present clinically as abscesses or mass lesions and morphologically mimic small round cell tumors like lymphoma.
• Accurate diagnosis of MS is challenging due to its varied presentations and potential to resemble other neoplasms.

Purpose of the Study:

• To investigate the clinical and laboratory features of myeloid sarcoma.
• To review histomorphological findings and differential diagnoses of MS.
• To assess the utility of immunohistochemistry (IHC) in diagnosing MS and identify key diagnostic markers.

Main Methods:

• Retrospective review of nine myeloid sarcoma cases diagnosed between January 2004 and December 2013.
• Analysis of clinical presentations, laboratory data, histopathology, and immunohistochemical findings.
• Evaluation of diagnostic markers for MS.

Main Results:

• None of the nine reviewed cases were clinically suspected as MS prior to diagnosis.
• The most common site was cervical lymph nodes, with a slight female predominance.
• Myeloperoxidase was identified as the most useful IHC marker, although leukocyte common antigen positivity caused diagnostic confusion with lymphoma.

Conclusions:

• Myeloid sarcoma should be considered in the differential diagnosis of unusual lymphoma-like neoplasms.
• Immunohistochemistry, particularly myeloperoxidase staining, is crucial for accurate MS diagnosis.
• Awareness of MS mimics is essential for appropriate patient management.