Hidradenoma papilliferum (HP) is a rare, benign cystic tumor that occurs predominantly in women aged 30 to 60 [1]. It is thought to originate from anogenital mammary-like glands, and therefore most commonly arises in the anogenital region with vulvar lesions reported approximately four times more frequently than perianal lesions [2]. Rare ectopic cases have also been reported, typically in the head and neck. Interestingly, while anogenital HP occurs almost exclusively in women, ectopic forms demonstrate a more balanced sex distribution, with nearly half of reported cases arising in men [3]. Here, we report a rare case of perianal HP in a 70-year-old man and review the literature on male HP. To our knowledge, this is only the fourth documented case of perianal HP in a male patient.

A 70-year-old man presented to our General Surgery clinic for a surveillance colonoscopy following previous findings of multiple tubular adenomas with low-grade dysplasia. During the procedure, a 2 cm polyp at the anal verge was incidentally identified but not removed (Figure 1). On return to clinic for discussion of the colonoscopy results, further assessment of the anal lesion was undertaken.

On examination, there was a highly pedunculated mass measuring approximately 2 cm in diameter at the 11 o’clock position. This lesion had reportedly been present for several months and had been recently increasing in size. There was no history of bleeding, pain, or pruritus. The patient’s past medical history included obesity, hypertension, and hypercholesterolemia.

Pathology Findings with IHC Confirmation

Surgical excision under general anesthesia was performed for histological evaluation. Informed consent was obtained from the patient for publication of this case report and accompanying images.

Gross Findings

Soft tissue specimen measuring 18 × 12 × 4 mm. The specimen was sectioned into five pieces for histological examination.

Histopathological Findings

Microscopic examination demonstrated a polypoid lesion with anal squamous epithelial covering (Figure 2). There was a well demarcated cystic lesion in the dermis lined by double layered epithelium with myoepithelial cells and inner cuboidal to columnar cells with apocrine snouts. Focally, there was an intramural solid area with tubular and cystic structures with benign eccrine and apocrine epithelium. Low papillary-like structures were also seen. There were no features of atypia or malignancy.

Immunohistochemistry (IHC) Findings

Immunohistochemistry showed tumor cells positive for GATA3, estrogen receptor, and progesterone receptor (Figure 3). Taken together, the morphological and immunohistochemical findings supported a diagnosis of HP.

Though first described in 1878, HP remains under-recognized, and its pathogenesis poorly understood. Typically presenting as an asymptomatic, slow-growing, raised nodule, some patients may report pain, pruritus, ulceration, and bleeding [2]. Lesions usually range from 0.5 cm to 2.5 cm in diameter, though sizes up to 10 cm have been reported [4].

Initially believed to arise from apocrine sweat glands, current evidence suggests that HP originates from anogenital mammary-like glands which are morphologically similar to breast tissue but are normally present in the interlabial sulcus [2],[5]. Like normal breast tissue, most lesions express estrogen and progesterone receptors and are influenced by female sex hormones, likely accounting for their predominance in post-pubertal women. Nevertheless, cases have also been documented in men and at ectopic sites. Ectopic HP is believed to arise from modified apocrine glands such as the glands of Moll at the eyelid margin or the ceruminous glands of the external auditory canal [6],[7]. While HP in women is strongly linked to the anogenital region, cases in men are more frequently ectopic. Additionally, the role of sex hormones in the pathogenesis of male HP is thought to be less significant than in women; however, our patient’s tumor did demonstrate positivity for both estrogen and progesterone receptors. More research is required to clarify the contribution of hormonal pathways to HP development in both sexes.

To better characterise HP in the male population, we conducted a review of the literature and identified 15 case reports of HP in men (Table 1). Only three of these cases involved the perianal region and thus, our case represents the fourth reported instance, highlighting the rarity of the condition.

Consistent with the literature, the majority of ectopic HP in our review occurred in the head and neck region (9/15, 60%) though other sites such as the arm, chest wall, and areola were also described [3],[8],[9]. We found that in men, perianal HP seemed to present at a higher mean age compared with ectopic HP (61.5 years vs 52.5 years). This observation differs slightly from existing literature, which reports that ectopic HP presents on average 10–20 years later than anogenital lesions [3]. Considering our exclusive focus on male patients and the limited number of reported cases, these findings should be interpreted with caution. Nevertheless, clinicians should be aware of the possibility of HP in an older male presenting with a perianal lesion.

The overall prognosis of HP is excellent, with surgical excision being curative in the vast majority of cases. Rare instances of local recurrence have been described [20], and there are occasional reports of malignant transformation in the forms of mammary-type hidradenocarcinoma, adenocarcinoma in situ and adenosquamous carcinoma [21],[22],[23]. Human papillomavirus (HPV), particularly HPV-16, has been detected in some of these lesions; however, a causal relationship has not yet been established [24].

In conclusion, we describe a fourth case of male perianal HP, a rare benign tumor most commonly found in women. It is often asymptomatic and may be overlooked or misdiagnosed due to its lack of distinctive clinical features. Surgical excision remains necessary for both definitive diagnosis and curative treatment.