EP568 - Extramammary Perianal Paget's disease: case report and literature review

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Purpose/Background: Extramammary Paget's disease (EMPD) is considered a rare intraepithelial adenocarcinoma affecting areas with apocrine glands, including the perianal area. Frequently, nonspecific perianal symptoms contribute to delay in diagnosis. Histopathology confirming perianal Paget’s disease (PPD) and wide local surgical excision are the gold standards in diagnosis and treatment of this rare disease, respectively. Here, we report an interesting case of PPD.

Methods/Interventions: A 71-years-old female patient presented with perianal soreness and biopsy proven poorly differentiated perianal carcinoma with in situ CK20 and CDX2 positive pagetoid components. Local examination revealed an anterolateral reddish irregular lesion, approximately 3.5 cm in diameter, starting at the anal verge and extending radially. Wide local excision of the lesion was performed. The patient recovered without any complication and was discharged home on the second postoperative day. Eight months after surgery, there was no evidence of other tumors and no recurrence of the PPD with close monitoring.

Results/Outcomes: PPD represents 20% of EMPD. The differential diagnosis includes lichen simplex, psoriasis, lichen planus, mycosis fungoides, Bowen's disease, and seborrheic dermatitis. Diagnosis is confirmed by histopathology. Immunohistochemistry can help in differentiating primary or secondary PPD as well as rule out pagetoid Bowen's disease and pagetoid malignant melanoma. Generally primary PPD is positive for CK7 and GCDFP15 and secondary PPD is often positive for CK20, and CDX2. Screening colonoscopy and computed tomography are usually obtained to exclude underlying malignancy. Gynecologic and medical oncology evaluations are also recommended prior to surgery. Operative treatment with intraoperative frozen sections is recommended for PPD. Local excision is recommended if negative margins can be achieved. For invasive or advanced cases, Abdominoperineal resection may be considered, especially for primary PPD. The goal is to maximize local control and minimize deformity and morbidity. Non-operative treatments include topical imiquimod, radiation therapy, photodynamic therapy, and carbon dioxide laser therapy. Distant metastatic disease may be treated with chemotherapy or individualized targeted approaches.

Conclusion/Discussion: Current data on diagnosis and management is based on limited, mostly gynecologic, literature. Wide local excision remains the treatment of choice. Local recurrence is common. Guidelines regarding follow-up is lacking in either PPD or gynecologic Paget’s disease. For local disease, the current recommendation is for biannual proctoscopy and digital exam for 5 years. For more invasive disease, annual inguinal lymph node exam and imaging should be performed as well. Future studies are warranted to explore mechanisms of pathogenesis and the natural history of different patterns of PPD to create standard guidelines for treatment and follow up.