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Abstract Perianal skin lesion is a common presentation with a wide range of differentials, including thrombosed external haemorrhoids, perianal abscess, perianal warts, lipoma and sebaceous cysts. Malignant lesions such as squamous cell carcinoma are uncommon but should be considered. Hereby, we present a diagnostically challenging case of a benign looking perianal lesion that ultimately revealed a rare condition. A 50-year old lady presented with a one-year history of perianal lump accompanied with intermittent pain, fresh bleeding and pus-like discharge. A digital rectal examination revealed a well-demarcated 4mm fleshy skin lesion, 2cm from anal verge at 7 o’clock position without surrounding area of inflammation. No lymph nodes were palpable on both groins. Differentials as mentioned above including an infected granuloma and fistula in-ano were considered. Pelvic MRI revealed a well-demarcated, benign-looking subcutaneous lesion. The lesion was excised under general anaesthesia and interestingly, the histopathology report revealed a diagnosis of Hidradenoma Papilliferum (HP) with no dysplasia or malignancy. Patient recovered well, reassured with the above findings and discharged home. HP is an uncommon, benign tumour that occurs in the anogenital region. It is more prevalent in Caucasian middle-aged females, as illustrated in our case. A definite diagnosis necessitates histopathological examination. The management includes a local excision of the lesion, and it is associated with good prognosis, with low chances of recurrence or malignant transformation. HP, although rare, should be included in the differentials of a perianal lump. A surgical excision or diagnostic biopsy should be performed at minimum.
Ng et al. (Sun,) studied this question.