Myeloid sarcoma: Clinical, Pathologic, and Molecular Findings

Area of Science:

• Hematology
• Oncology
• Pathology

Background:

• Myeloid sarcoma is a neoplasm of myeloid blasts at extramedullary sites, often considered equivalent to acute myeloid leukemia (AML).
• The definition of myeloid sarcoma excludes extramedullary AML not forming a mass, leading to less defined management strategies.
• The pathogenetic relationship and clinical significance of extramedullary AML versus myeloid sarcoma remain underexplored.

Purpose of the Study:

• To review the clinicopathologic, immunophenotypic, and molecular findings of myeloid sarcoma.
• To discuss the differential diagnosis of myeloid sarcoma.
• To explore the relationship between myeloid sarcoma and non-mass forming extramedullary AML.

Main Methods:

• Literature review of clinicopathologic, immunophenotypic, and molecular findings.
• Analysis of studies on the MAPK/ERK pathway in myeloid sarcoma and extramedullary AML.
• Discussion of differential diagnoses and pathogenetic relationships.

Main Results:

• Recent studies implicate the MAPK/ERK pathway in the pathogenesis of myeloid sarcoma and extramedullary AML.
• Extramedullary myeloid disease sites may evolve independently from medullary AML due to microenvironmental factors and immune evasion.
• Distinct pathogenetic mechanisms may underlie mass-forming myeloid sarcoma and non-mass forming extramedullary AML.

Conclusions:

• Understanding the distinct evolution and pathogenesis of extramedullary myeloid neoplasms is crucial for accurate diagnosis and management.
• Further research is needed to clarify the relationship between myeloid sarcoma and extramedullary AML.
• The MAPK/ERK pathway represents a potential therapeutic target in these conditions.