eP567 - Basal Cell Carcinoma Where the Sun Don't Shine

Purpose/Background: Basal Cell Carcinoma (BCC) is the most common non-melanoma skin cancer worldwide. Approximately 80% of all BCC cases are localized to sun exposed areas, such as the head and neck, as ultraviolet light is the most important etiological factor. Perianal BCC accounts for less than 0.2% of all BCC cases (Tsai, 2023), and roughly 0.2% of all anorectal neoplasms (Welton, 2007). Here we report a case of a 72-year-old female with perianal BCC successfully treated with local excision and flap adjacent tissue transfer.Methods/Interventions: .Results/Outcomes: A 71 year old female presented to colorectal surgery for evaluation of a perianal lesion of several years duration. The patient believed the lesion was secondary to enlarging hemorrhoids, which had been diagnosed on routine colonoscopy several years prior. The patient could not recall how long the lesion had been present, but a 2019 screening colonoscopy had no mention of a perianal lesion. She received treatment for suspected dermatitis in the region with Clotrimazole and Betamethasone two year prior without full resolution. The patient denied a significant personal or family history of anogenital warts, sexually transmitted disease, malignancy, or inflammatory dermatoses prior to 2021. Upon physical exam, the patient had a 2.0 x 2.0cm red, slightly raised, circular lesion 1.5 cm lateral to the right side of the anal verge. The lesion was painless, without bleeding, induration, or drainage. Anoscopy revealed Grade 1 internal hemorrhoids without fistula or other anorectal pathology. A 4mm punch biopsy was performed in the center of the lesion and revealed nests of atypical basaloid keratinocytes surrounded by myxoid stroma. Peripheral palisading, individual necrotic keratinocytes, and notable mitotic figures were present consistent with Basal Cell Carcinoma. The patient subsequently underwent a combined local excision and closure with “hatchet” flap adjacent tissue transfer. The patient was discharged the same day with weight off-loading precautions for the incision. Operative pathology revealed a completely excised 1.9 x 1.8cm lesion, 4mm from the nearest margin, extending 4mm into the dermis. Pathology was again consistent with Basal Cell Carcinoma. Postoperative recovery was uneventful without wound complications. No additional therapy was deemed necessary.Conclusion/

Discussion: BCC in the perianal region is extremely rare as it most commonly occurs on sun-exposed cutaneous surfaces. Diagnosing perianal BCC can present a considerable challenge due to its resemblance to other more common anorectal pathology. Both patients and physicians may delay treatment for what is considered localized irritation/itching, or other simple inflammatory dermatoses, rather than cancer (Collins, 2010). Biopsy of all suspect lesions within the perianal region is recommended due to the innocuous appearance of BCC (Narendra, 2010). Upon diagnosis, a thorough clinical exam should be performed due to its increased association with other skin lesions. Wide local excision with negative margins is the standard treatment of choice for most patients and has good long-term results. Most BCCs are localized with metastasis rates well below 0.5%, a mortality rate of less than 0.1% and a 5-year survival of 100%. For patients with BCC who are not surgical candidates, definitive radiotherapy is the preferred treatment option, however recurrence rates have been found to be upwards of 7.4% (Tsai, 2023)."Perianal Lesion

Excision of Perianal Lesion

Excision of Perianal lesion with 4mm margins circumferentially
Hatchet Flap Adjacent Tissue Transfer Mapping

Completed Hatchet Flap Adjacent Tissue Transfer
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