Surgical and radiation therapy management of recurrent anal melanoma

Abstract

Background: Melanoma of the anorectal mucosa is a rare but highly aggressive tumor. Its presenting symptoms are frequently confused with hemorrhoids, thereby causing a delay in diagnosis. Anorectal melanoma carries with it a very poor prognosis. There is a paucity of data investigating management options for anorectal melanoma, and even fewer data reporting recurrent or refractory cases.

Case presentation: This case documents a 41-year-old female with a long history of hemorrhoids presenting with anorectal discharge. She was incidentally found have anorectal melanoma following surgical resection. Systemic diagnostic work-up demonstrated PET-avid lymphadenopathy in her right groin. She underwent right groin dissection. However, seven months later she recurred in her right groin and a new recurrent mass was found in her pelvis. She underwent a second groin dissection and resection of the pelvic recurrence. This was followed by a course of hypofractionated radiation therapy then systemic immunotherapy.

Discussion: Surgery has been the mainstay of treatment. However, the extent of surgery has been the topic of investigation. Historically, radical resections have been performed but they result in high rates of post-operative morbidity. Newer studies have compared radical resection with wide local excisions and found comparable outcomes. Anorectal melanoma is frequently a systemic disease. The ideal systemic therapy regimen has not yet been determined but numerous studies show a benefit to multi-agent treatments. Radiation therapy is typically given in the post-operative or palliative setting.

Conclusions: Anorectal mucosal melanoma is a very rare but aggressive disease with a poor prognosis. The overall treatment goal should strive to optimize quality of life and tumor control while minimizing treatment-related morbidities.

Keywords: Anorectal; radiation treatment; recurrent anal melanoma; surgery.

Figure 1

Surgical pathology from the initial hemorrhoidectomy revealed anal mucosal melanoma with melanoma pigment visible at (A) low power and (B) high power.

Figure 2

PET-CT scan following the initial hemorrhoidectomy showing hypermetabolic FDG uptake in a right inguinal node, suspicious for metastatic disease (arrow).

Figure 3

PET-CT done after superficial right groin dissection showing hypermetabolic FDG uptake in the right groin (short arrow) as well as a hypermetabolic soft tissue mass in the left hemipelvis (long arrow). Both were suspicious for recurrent.