Purpose or Case Report: Background: Granular cell tumors (GCT) are rare Schwann cell-derived soft tissue tumors typically presenting as a solitary, painless nodule in adults in the 4th to 6th decades of life, rarely presenting in children. GCT most commonly originate from gastrointestinal mucosa of the tongue or oral cavity, and are 2-3 times more common in women. While generally benign, approximately 2% of cases may be malignant; therefore, GCTs are typically treated with local surgical control.
Case: A 7-year-old male with sickle cell trait presented to clinic for a painless “pea-sized lump” on his penile shaft, which had been present since infancy but had recently grown larger. Ultrasound demonstrated a 1.8 cm lenticular-shaped mass on the dorsal mid shaft of the penis superficial to the fascial borders of the cavernous cavernosum. There was mild internal vascularity, but no invasion past fascial borders, surrounding soft tissue changes. On MRI, the mass was uniformly T1 iso-intense and T2 slightly hyperintense, with slight postcontrast enhancement. The mass was well-circumscribed, wrapped around the corpus cavernosum without invasion of the tunica albuginea, and exhibited uniform restricted diffusion, calcification, or internal fat. No lymph node involvement was noted on imaging. Surgical resection 8 months later noted a 3 cm mass, which now extended into the glans, with pathology consistent with benign GCT, with positive staining for S-100, CD68, SOX10, and calretinin, Ki-67 of 1%, and negative for SM actin. Due to depth of glans penetration, R2 resection was achieved based on the pediatric urologist’s decision to spare the glans, rather than performing a more aggressive distal penectomy. Post-operative MRI 4 months later demonstrated residual tumor with interval reduction in mass size. Additional investigation of the patient’s past medical history revealed that a benign GCT had been removed from the inside of his lip the previous year which helped support the final histopathologic diagnosis. While multifocal GCTs have been described in genetic syndromes, this patient had not undergone genetic testing to date.
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Conclusions: Conclusions: Pediatric penile tumors are extremely rare with fewer than 20 GCTs described. This case is one of the youngest cases of penile GCT reported. Furthermore, this case contains multi-modality imaging of the lesion to better which may prove informative for future identification of this rare tumor.