Anal Melanoma: An Aggressive Malignancy Masquerading as Hemorrhoids

Michael W. Felz, MD, Ginger B. Winburn, MD, Andre M. Kallab, MD, Jeffrey R. Lee, MD, Departments of Family Medicine, Surgery, and Medicine (Section of Medical Oncology), Medical College of Georgia, and the Department of Pathology, Veterans Affairs Medical Center, Institute of Molecular Medicine and Genetics, Augusta, Ga

South Med J. 2001;94(9) 

In This Article

Case Reports

Case 1

A 26-year-old black male bricklayer from central Georgia was seen in December 1995 with 6 months of painful defecation and rectal bleeding, diagnosed as internal hemorrhoids and refractory to medical management. A palpable, tender 5 cm mass was detected on digital rectal examination (DRE), thought to be a thrombosed hemorrhoid, and excised transanally in January 1996. Pathology of the resected specimen revealed anal melanoma with 8 mm of tumor thickness. No evidence of distant metastasis was present. He received adjuvant interferon-alpha (IFN-) immunotherapy. In July 1996, a left groin mass developed. At excision, necrotic metastatic melanoma was detected. One of 31 inguinal nodes was positive for melanoma. At follow-up in August 1997, at least 10 pulmonary metastases 1 to 3 cm in diameter were found. He received radiation therapy, interleukin-2 (IL-2) and IFN-

immunotherapy without tumor response. Relentless clinical deterioration followed, with widespread metastases to lungs and bone. The patient died in February 1999, 37 months after diagnosis.

A 58-year-old white male prison inmate from eastern Georgia had 6 months of rectal pain and bleeding, diagnosed as hemorrhoids in April 1998 and refractory to medical management. A 20-lb weight loss was documented. A tender, pigmented, prolapsing mass was palpable by DRE (Fig 1). Colonoscopy in May 1998 showed a 5 cm fungating, ulcerated mass 2 cm from the anal verge in the anterior position. Biopsies revealed anal melanoma with 18 mm of tumor thickness, deeply invasive into intestinal wall and vascular structures (Fig 2). Hepatic and pulmonary metastases were observed on computed tomography (CT). The patient had abdominoperineal resection (APR) in June 1998 for palliation of severe anal pain, bleeding, and near obstruction by the mass located just above the dentate line (Fig 3). Biopsy of pigmented liver nodules and 14 perirectal lymph nodes was positive for metastases. He received three cycles of dacarbazine, cisplatin, and carmustine, with tamoxifen. Disease progression was rapid despite aggressive intervention. He died of widespread metastatic melanoma to liver and lungs in March 1999, 10 months after diagnosis.

Figure 1.

(Case 2) Pigmented, prolapsing anal melanoma.

Figure 2.

(Case 2) Biopsy shows sheets of malignant melanoma with pagetoid invasion (arrow) of overlying squamous mucosa and lymphatic invasion (arrowhead). (Hematoxylin & eosin, original magnification x 100). Inset: Brown chromagen deposition in nests of malignant cells within squamous mucosa. (HMB-45 immunohistochemical stain, original magnification x 200).

Figure 3.

(Case 2) APR specimen shows deeply pigmented, fungating mass at dentate line.

Figure 4.

(Case 3) Ulcerated, prolapsed anal melanoma (arrow).

A 58-year-old white male nuclear engineer from western South Carolina was seen in November 1998 with 3 months of rectal bleeding and a prolapsing mass, diagnosed as hemorrhoids and refractory to medical management. A pedunculated, nontender mass was palpable within the anal orifice on DRE (Fig 4). Colonoscopy showed a 4 cm ulcerated, fungating mass (Fig 5). Biopsy confirmed amelanotic melanoma. Multiple liver metastases were detected by magnetic resonance imaging (MRI) (Fig 6), with increased signal intensity on T1-weighted images consistent with melanin within the lesions. Wide local excision of the rectal mass was done to control bleeding and prolapse. Pathologic specimens revealed 7 mm of tumor thickness. Three cycles of biochemotherapy with cisplatin, tamoxifen, IFN-

, and IL-2 were administered. At follow-up, more extensive hepatic metastases were detected by MRI, with new metastases in right inguinal nodes, lungs, and multiple ribs. High-dose IFN-

was administered for 4 weeks. He was evaluated for high-dose IL-2 immunotherapy at the National Cancer Institute, but his condition deteriorated rapidly and he died in July 1999, 8 months after diagnosis. At autopsy, widespread metastases were detected in liver, spleen, periaortic and inguinal nodes, lungs, vertebral column, ribs, pons, and the cerebral cortex.

Figure 5.

(Case 3) Retroflexed sigmoidoscopic view of nodular 4 cm anal melanoma (arrowheads).

Figure 6.

(Case 3) Unenhanced T-1 weighted magnetic resonance imaging shows large homogeneous low signal intensity metastasis (arrowhead) and multiple high signal intensity lesions (arrows) typical of metastatic melanoma.

A 59-year-old white male utilities worker from eastern Georgia was seen in June 1999 with 4 months of rectal fullness and bleeding, diagnosed as hemorrhoids and unresponsive to medical management. Bilateral inguinal adenopathy was present. On DRE, a 6 cm tender, partially pigmented, prolapsing mass (Fig 7) was palpable at 2 cm inside the anal canal. Biopsy of the mass showed anal melanoma with tumor thickness exceeding 5 mm. Needle biopsy of inguinal lymph nodes showed metastatic melanoma, and chest CT scan showed multiple pulmonary metastases. Despite chemotherapy and radiotherapy, widespread metastases developed, metastases to the gastric fundus resulted in massive gastrointestinal hemorrhage, and he died in December 1999, 6 months after diagnosis.

Figure 7.

(Case 4) A 6 cm prolapsed, nodular, pigmented anal melanoma.

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