Rhabdomyosarcoma mimicking lymphoma

Area of Science:

• Oncology
• Pediatric Oncology
• Medical Imaging

Background:

• Rhabdomyosarcoma (RMS) is a common soft tissue sarcoma in children, but metastatic disease at diagnosis is infrequent (<25%).
• Metastatic RMS presents with diverse clinical manifestations, posing diagnostic challenges.

Observation:

• A 17-year-old male presented with weight loss, fever, and bone pain, leading to admission for severe hypercalcemia.
• Diagnosis of RMS was confirmed via immune-phenotyping of a metastatic lymph node biopsy; the primary tumor site remained unidentified.
• Bone scan revealed diffuse bone metastases and notable soft tissue technetium uptake attributed to extra-osseous calcification.

Findings:

• Metastatic rhabdomyosarcoma can present with symptoms mimicking lymphoproliferative disorders.
• Severe hypercalcemia and diffuse bone metastasis were key features in this case.
• Extra-osseous calcification contributed to soft tissue technetium uptake on bone scan.

Implications:

• Clinicians should consider metastatic RMS in the differential diagnosis of young adults presenting with unexplained hypercalcemia and bone pain.
• Awareness of RMS's varied presentations is crucial for timely diagnosis and management.
• This case highlights the importance of comprehensive diagnostic workup for rare pediatric malignancies.