Deep Cavernosal Melanoma Without Clinically Evident Mucosal or Cutaneous Involvement: A Case Report

Area of Science:

• Urology
• Oncology
• Dermatology

Background:

• Penile melanoma is an extremely rare malignancy, accounting for less than 0.1% of all melanomas.
• It typically originates from the glans, foreskin, or urethral meatus.
• Deep cavernosal involvement without apparent cutaneous, mucosal, or urethral disease is an unusual and challenging presentation.

Purpose of the Study:

• To report an unusual case of penile melanoma with deep cavernosal involvement.
• To highlight the diagnostic and therapeutic challenges associated with this rare presentation.
• To emphasize the aggressive nature of deeply located penile melanoma.

Main Methods:

• A 23-year-old male presented with penile induration and pain.
• Magnetic Resonance Imaging (MRI) revealed a lesion predominantly involving the corpus cavernosum.
• Diagnosis was confirmed by excisional biopsy, followed by partial penectomy, bilateral sentinel lymph node dissection, and systemic staging with CT and PET-CT.

Main Results:

• The initial biopsy showed tumor at the resection margin; epidermal sampling was absent.
• Systemic staging initially showed no metastatic disease.
• One year later, 18F-FDG PET-CT revealed metastatic disease including retroperitoneal, iliac, inguinal lymphadenopathy, sternal manubrium lesions, and a pulmonary nodule. Immunotherapy showed limited response.

Conclusions:

• This case highlights an unusual penile melanoma presentation involving the corpus cavernosum without external lesions.
• The lack of epidermal sampling precluded ruling out a regressed primary lesion.
• Deeply located penile melanomas exhibit aggressive behavior, necessitating meticulous clinicopathological correlation and multidisciplinary care.