Dear Editor, Hidradenoma papilliferum is an uncommon, slow-growing cutaneous adnexal tumour, affecting adult women in their fourth or fifth decade.1 It is considered to be arising from the anogenital mammary-like glands.2 Although this tumour is benign in nature, occasional cases of malignant transformation have been reported earlier in the literature.3 A 43-year-old female presented to the gynaecology outpatient department (OPD) with complaints of a small swelling in the vulvar region on the right side. She had noticed the swelling 6 years back but had not reported it earlier, because of the painless nature of the swelling. The swelling was initially tiny, which later increased gradually in size. The patient had no history of itching, discolouration, discharge and ulceration. On clinical examination, the swelling was present over the right labia majora with a size of about 5 mm × 5 mm × 3 mm. Skin over the swelling appeared normal. Due to the cystic nature of swelling along with the peculiar location, a provisional diagnosis of right labial cyst (likely Bartholin’s cyst) was rendered by the clinician. The patient underwent excision biopsy of the swelling, which was subjected to histopathological examination. On microscopy Figure 1, well-circumscribed proliferation was noted in the dermis, showing papillary architecture. The papillae showed the presence of fibrovascular cores and the presence of luminal cuboidal-to-columnar cells and abluminal clear (myoepithelial) cells. The luminal cells were having moderate amount of eosinophilic cytoplasm and round-to-oval nuclei, with few having conspicuous nucleoli. The abluminal cells had abundant clear cytoplasm and oval nuclei had uniformly dispersed chromatin. No granuloma or giant cells were seen. No areas of necrosis were noted. Based on these characteristic histomorphological features, the diagnosis of hidradenoma papilliferum was given.Figure 1: Photomicrographs from the slides prepared from the submitted histopathology specimen. (a) Dermal-based proliferation composed of tubulopapillary architecture is seen on low power (H and E, ×40). (b) The tubular predominant part of the tumour is noted here (H and E, ×100). (c) Papillary projections within the tumour. Fibrovascular cores within the papillae are better appreciated in the central finger-like projection (H and E, ×100). (d) The luminal side of the papillae is seen lined by cuboidal-to-columnar epithelial cells. The abluminal myoepithelial cells have abundant clear cytoplasm (H and E, ×400)The differential diagnosis considered based on the cystic appearance and papillary architecture of the tumour was syringocystadenoma papilliferum. However, our case showed no connection to the overlying epithelium, and the proliferation was dermal-based only. The stroma in cases of the syringocystadenoma papilliferum shows the presence of numerous plasma cells, which was not seen in our case. Hence, the possibility of the latter was negated. The patient was followed up for 3 months, post-surgery in the gynaecology OPD, and she remained asymptomatic for this period. No recurrence was noted. Vulvar hidradenoma papilliferum was first described in the year 1878.4 In a retrospective study spanning over 5 years at one of the tertiary care centres in India by Tiwana et al., only five cases of adnexal tumours of the vulva were seen, out of which, only two cases were of hidradenoma papilliferum.5 The median age of the patients has been described to be 50 years. The cases may present to the dermatologist. However, the diagnosis of hidradenoma papilliferum remains challenging even after dermoscopy. However, the dermoscopy helps rule out sinister differential diagnosis like melanoma. The patient usually presents with painless swelling, while a few cases may have slight discomfort and irritation. Prompt excisional biopsy remains the suggested treatment. Occasional cases of malignant transformation have been described earlier, wherein vulvar apocrine hidradenocarcinoma and vulvar adenosquamous carcinoma have developed from hidradenoma papilliferum.3 Histomorphological examination remains diagnostic; however, the immunohistochemical profile of this benign entity has also been described. The luminal epithelial cells are found to express ER, PR, CK7 and EMA, whereas the myoepithelial cells express p63, S100 and CD10. To conclude, vulvar hidradenoma papilliferum is an uncommon, slow-growing, benign adnexal tumour that may present as a cystic vulvar swelling. Clinicians should be aware of this entity when considering differential diagnoses. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Pendharkar et al. (Thu,) studied this question.