eP169 - Perianal Paget's Disease

Purpose/Background: Over 100 years have passed since perianal Paget’s disease (PPD) was first described, however its rarity and nonspecific symptoms make it a commonly misdiagnosed malignancy. PPD represents 20% of extramammary Paget’s disease, but less than 1% of anal disease. PPD often presents initially as pruritis and is often accompanied by a slowly enlarging, asymmetrical patch characterized by erythema, hyperpigmentation, or leukoplakia. Given these findings, it is commonly misdiagnosed as an inflammatory condition, resulting in significant delays in treatment.

Though perianal Paget’s disease can be primary, it is secondary to underlying malignancy in 33-86% of cases. The most common underlying malignancy is colorectal adenocarcinoma, though anal, tubo-ovarian, and skin cancers have also been reported. Underlying invasive carcinomas carry poor prognosis. Most cases are treated with either wide local excision or abdominoperineal resection with wide excision of the cutaneous lesion, when associated with underlying carcinoma of the anus or rectum. Even with surgery, 42-61% of cases of PPD recur.

We present the case of a 74 year old female previously diagnosed with perianal lichen simplex chronicus and found to have perianal Paget’s disease at the anal margin with skin changes extending to the inferior vaginal introitus.Methods/Interventions: Chart ReviewResults/Outcomes: A 74 year old female presented to clinic with history of cutaneous lichen planus and perianal lichen simplex chronicus managed by her dermatologist Primary complaint of symptomatic hemorrhoids. Despite a course of conservative measures, the patient's symptoms persisted, prompting an exam under anesthesia where biopsies were taken. Pathology demonstrated skin with pagetoid spread of adenocarcinoma. Following negative workup for additional disease, the patient underwent a 2nd exam under anesthesia for mapping biopsies and surgical planning. Disease was noted to extend to the inferior vaginal introitus and thus, an abdominoperineal resection end colostomy formation was planned in conjunction with the Plastic Surgery Service for flap reconstruction.Conclusion/

Discussion: Perianal Paget's disease is a rare tumor, often misdiagnosed and identified late in the disease course. After obtaining initial tissue diagnosis, it is crucial to completely workup the patient with endoscopic and computerized tomography modalities to rule out synchronous and metastatic disease. Many treatments options have been proposed--wide local excision is the preferred modality when technically feasible. Given the aggressive nature of this disease and its required resection, complex reconstruction with advancement flaps are often employed for improved cosmesis and infection prevention."Specimen: Anal Verge, Left

Cells with abundant pale cytoplasm extending up through the skin layers, consistent with Paget Cells
Specimen: Anal Verge, left (higher power view)

Cells with abundant pale cytoplasm extending up through the skin layers, consistent with Paget Cells
Specimen: Anal Verge, Posterior. CK20 stain

Ck20 stain--Tumor Cells with CK20 stain. Positive for tumor cells (indicated by the brown color)"