Perianal basal cell carcinoma (BCC) is a rare occurrence, with limited documented cases in the existing literature. The precise etiology contributing to its onset remains inadequately elucidated. Macroscopically, perianal BCC often exhibits atypical features, potentially leading to diagnostic challenges. Histopathological examination plays a crucial role in distinguishing BCC from other cutaneous lesions in this region. Despite its localized nature, perianal BCC generally carries a favorable prognosis characterized by a gradual progression. However, diligent follow-up is essential to mitigate the risk of recurrence. Our clinical observation highlights a noteworthy yet uncommon manifestation. The patient, a 64-year-old male, presented with a persistent perianal lesion evolving over a three-month period. Symptoms included intermittent bleeding and purulent discharge, exacerbating the clinical picture. A biopsy was subsequently performed, confirming the diagnosis of basal cell carcinoma. Following this, the patient underwent external beam radiation therapy as part of the treatment regimen.

UNASSIGNED: The large resection area of perianal tumor makes the skin defect hard to reconstruct. The keystone flap has demonstrated a growing application in skin defects. Herein, we aimed to explore the efficacy of keystone flap in the repair of skin defect after perianal tumor resection.
UNASSIGNED: This study is a retrospective review of patients diagnosed with perianal tumor from January 2010 to November 2021. A standardized data collection template was used to collect variables. The detailed process of the reconstructive surgery is carefully described in this article. After surgery, the healing process was closely observed.
UNASSIGNED: Twenty patients underwent keystone flap repair. The average wound size before closure measured 3.5 × 4.9 cm2. Primary wound healing was achieved, and the flap survived during the follow up period, which ranged from 6 to 24 months. No severe complications occurred; slight edema was noticed in one patient.
UNASSIGNED: The application of keystone flap is a promising way to repair skin defect after tumor removal, and the complications rate was low after surgery. It can be concluded that this method is an effective and reliable way to repair perianal skin defect.

Granular cell tumors (GCTs) are rare submucosal neoplasms, with tumors in the oral mucosa accounting for about a third of all cases. In contrast, GCT is a rare anal neoplasm, with fewer than 30 cases of perianal GCT reported in the literature. We report the case of a 36-year-old woman with a perianal lump with no obvious local lesion as the main clinical complaint. The tumor was completely resected and histologically confirmed as a GCT. The patient remained under continuous follow-up. GCT is difficult for surgeons and pathologists to diagnose, and biopsy and immunohistochemical analysis are prerequisites for an accurate diagnosis. An integrated understanding of GCT in terms of its differential diagnosis will contribute to better identification and more appropriate treatment of this disease.

Extramammary Paget disease (EMPD) involving the perianal region is rare and challenging to manage. Primary EMPD involves stand-alone noninvasive lesions within the epidermis, while secondary EMPD involves phenotypically similar lesions derived from separate underlying malignancies. Differentiating between primary and secondary EMPD is challenging when no underlying malignancies are detected during workup. Continued reporting of perianal EMPD cases is encouraged so that risk stratification can be improved and patients can be managed with an appropriate level of aggressiveness. Herein, we report the case of a 74-year-old woman who chose aggressive surgical management after being diagnosed with perianal pagetoid intraepithelial carcinoma from a suspected occult underlying primary colorectal tumor.

Mucinous adenocarcinoma of the perianal region is an oncologic rarity posing a diagnostic and therapeutic dilemma for treating oncologists due to very few reported cases without definite therapeutic guidelines. It accounts for 2% to 3% of all gastrointestinal malignancies and are historically known to arise from chronic anal fistulas and ischiorectal or perianal abscesses. We hereby report a sporadic and interesting case of perianal mucinous adenocarcinoma in a 56-year-old male initially treated with alternative medicines and local surgery for recurrent fistula in ano of 2 years duration. He presented with complaints of discharging growth in perianal region, painful defecation associated with occasional blood mixed stools of 6 months duration. Incisional biopsy from the ulcer revealed mucinous adenocarcinoma. Contrast enhanced computed tomography (CT) scan and whole body positron emission tomography (PET) scan showed a localized perianal growth which was further confirmed with colonoscopy. With no pre-set treatment protocol for this rare entity, he was managed with neo-adjuvant concurrent chemo-radiation (CCRT) followed by abdominoperineal resection (APR) and adjuvant chemotherapy. Presently he is on 3 monthly follow-up since last 1 year post APR and adjuvant chemotherapy without any evidence of recurrence or distant metastasis. To the best of knowledge, our report may be one of the rarest cases of this disease entity where the duration of anal fistula was merely 2 years in contrast to the established criteria that the fistula precedes carcinoma by at least 10 years.

A case of Papular acantholytic dermatosis restricted to the perianal area is being reported in a 26 year old male without involvement of the genitalia, groin and upper thighs for the first time in English literature. The patient presented with long standing grayish white confluent papules with eroded areas in the perianal region which were asymptomatic for a long time before the area got macerated. He did not respond to many weeks of topical steroids but is now showing improvement with topical tacrolimus ointment 0.1% applied twice daily. This entity appears to be very uncommon and also underreported. It is also suggested that this entity be included in the long list of non venereal anogenital lesions as it may mimic perianal warts or molluscum contagiosum.