Systemic rhabdomyosarcoma with diffuse bone marrow involvement. Case report of an unusual presentation

Area of Science:

• Pediatric Oncology
• Hematology
• Pathology

Background:

• Rhabdomyosarcoma, a soft tissue sarcoma, typically presents as a localized tumor.
• Systemic rhabdomyosarcoma at initial diagnosis is exceptionally rare.

Observation:

• A 12-year-old girl initially presented with symptoms mimicking hematologic malignancy.
• Diffuse lytic bone lesions and bone marrow findings of primitive cells with erythrophagocytosis were noted.
• A subsequent diagnosis of alveolar rhabdomyosarcoma was confirmed from a soft tissue mass.

Findings:

• Retrospective analysis, including electron microscopy, identified primitive marrow cells as likely rhabdomyoblasts.
• The patient experienced a rapid clinical decline characterized by bone destruction and hypercalcemia.
• The alveolar histologic subtype is associated with aggressive disease progression.

Implications:

• Widespread rhabdomyosarcoma without an obvious primary tumor poses a significant diagnostic challenge.
• This case highlights a rare, aggressive subgroup of rhabdomyosarcoma with a rapidly fatal course.
• Understanding rare presentations is crucial for timely diagnosis and management of pediatric cancers.