HIV related anal canal squamous cell carcinoma refractory to chemo radiation needing abdominoperineal resection is a locally aggressive disease requiring muscle flap.

Ben Selvan, MD1, Andrew Zheng2, David Stein, MD1, Juan L Poggio, MD1. 1Drexel University College of Medicne, 2Jefferson college of medicine

Background. Anal canal squamous cell carcinoma (SCC) historically has a complete response rate up to 80-90% and average Cd4 count at the time of diagnosis is above 300. Failed or recurrent tumors following modified Nigro treatment requiring muscle flap to cover the perianal skin defect is limited in the literature. More over the relationship between Cd4 count and predicting the aggressive nature of the tumor is limited.

Methods. This is a retrospective study from 2011- 2014 on patients diagnosed with HIV related SCC of the anal canal who failed modified chemoradiation therapy requiring abdomino perineal resection (APR). We analyzed factors such as smoking, CD4 count, grade of tumor, HARRT therapy and extent of the perianal skin involvement at the time of diagnosis of anal SCC. We also compared the average perianal skin involvement between HIV and non HIV patients requiring APR.

Results. There were four patients who met these criteria and three were males and one female; all were active smokers and non complaint on HAART. We had two non HIV patient requiring APR as control and were smokers as well. The average CD4 count at the time of diagnosis was 245[range; 189-285]. All the initial biopsy showed well to moderately differentiated tumors. The average time of developing anal SCC was 13 years following the diagnosis of HIV. The indication for surgery was persistent disease after completion/refractory to Nigro protocol except one patient who had recurrence. The surgery done was APR with wide local excision of the perianal skin. The defect was so large to close primarily and it needed a muscle flap to cover. Vertical rectus abdominus flap with skin [VRAM] was used as local muscle flap. They all were dedifferentiated from moderate to poor grade tumors at the final APR resection specimen. The perianal skin involvement was limited at the time of initial diagnosis but all four had extensive perianal skin involvement at the time of surgery and was progressive. There were multiple satellite nodules on the skin making a wider excision in HIV patients than non HIV patients. The average perianal skin involvement by tumor was 108.6 square centimeters [range; 39-225] and 10 square centimeters [range;12-8] in non HIV patient.

Conclusion. Though this series is limited by small numbers, Squamous cell carcinoma of the anal canal in HIV patients which is refractory to the Nigro protocol is associated with low CD4 counts (less than 250) and it dedifferentiates to a more aggressive tumor with extensive skin involvement requiring a muscle flap to cover the defect. This observation needs further clinical study and research to identify a genetic/molecular marker which could predict a refractory anal scc so an alternate chemo based treatment or upfront surgery could be considered.

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