Perianal and Perineal Spindle Cell Variant of Embryonal Rhabdomyosarcoma in an Infant

Area of Science:

• Pediatric Oncology
• Surgical Pathology
• Rare Tumor Variants

Background:

• Embryonal rhabdomyosarcoma (RMS) is a rare pediatric malignancy.
• The spindle cell variant is an uncommon subtype with distinct histological features.
• Perianal tumors in infants require careful differential diagnosis.

Observation:

• A 3-month-old male infant presented with a firm perianal mass.
• Surgical excision of the 5 cm × 3 cm × 2 cm mass was performed.
• Histopathological examination revealed a malignant spindle cell neoplasm.

Findings:

• Biopsy confirmed embryonal rhabdomyosarcoma.
• Immunohistochemical (IHC) stains for vimentin, myogenin, spinal muscular atrophy, and muscle-specific actin were positive.
• Results were consistent with the spindle cell variant of embryonal RMS.

Implications:

• Early diagnosis and surgical management are crucial for pediatric perianal masses.
• Accurate histological and IHC characterization is vital for subtyping RMS.
• Understanding rare variants like this spindle cell type can inform treatment strategies and prognosis.