Undifferentiated rhabdomyosarcoma with lymphoid phenotype expression

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Poorly differentiated rhabdomyosarcomas are typically identified by the lack of lymphoid markers (e.g., immunoglobulin, CD20).
• Lymphoid neoplasms are characterized by lymphocytic markers and morphology.

Purpose of the Study:

• To investigate cases of rhabdomyosarcoma initially misdiagnosed as lymphoid neoplasms.
• To highlight the importance of considering rhabdomyosarcoma in undifferentiated tumors with a lymphoid phenotype.

Main Methods:

• Morphological and immunohistochemical analysis of tumor cells.
• Detection of lymphoid and muscle-specific markers.
• Cytogenetic analysis for chromosomal translocations, specifically t(2;13).

Main Results:

• Three cases of alveolar rhabdomyosarcoma presented with a lymphocytic phenotype.
• Two cases showed the characteristic t(2;13) chromosomal translocation.
• All cases were positive for muscle markers (muscle-specific actin, myoglobin, MyoD1, desmin) upon further testing and recurred in the chest wall.

Conclusions:

• The presence of a lymphoid phenotype in tumor cells does not exclude a diagnosis of rhabdomyosarcoma.
• Alveolar rhabdomyosarcoma can exhibit a lymphoid phenotype, necessitating comprehensive diagnostic evaluation including cytogenetics and muscle marker assessment.