Poroid Hidradenoma: A Two-Case Report and Literature Review

Poroid Neoplasms: A Clinicopathological Study of 13 Cases

Introduction

Poroid neoplasms (PN) are a heterogeneous group of tumors deriving from sweat glands and folliculo-sebaceous units. Their histological classification and clinical features are challenging. Our aim was to report clinicopathological features of poroid neoplasms.

Methods

It is a retrospective study including all cases of poroid neoplasms registered at our Pathology laboratory of Niamey National Hospital (February 2020-February 2024).

Results

We registered 13 cases of benign poroid neoplasms: 10 classic poromas (CP) (76.9%), 2 poroid hidradenomas (PH) (15.4%) and 1 dermal duct tumor (DDT) (7.7%). Nine cases (69.2%) had preoperative clinical diagnosis of malignancy. The mean age was 41.1 years (range of 12-70 years) with a slight female predominance. Only 4/13 cases (30.8%) had classical palmoplantar locations. The tumors mean size was 3.7 cm (range of 0.4-8 cm). Clear cells were present in 7 cases (53.8%), apocrine ductal differentiation (mixed or pure) in 6 cases (46.2%), keratin horns in 2 cases (15.4%), squamous eddies in 6 cases (46.2%), melanin pigments in 1 case (7.7%) and sebaceous differentiation in 2 cases (15.4%).

Conclusions

Unlike what is classically reported, our study shows that apocrine ductal differentiation, younger age and non-palmoplantar locations are common in poroid neoplasms.

Poroid Hidradenoma: Case Report and Comprehensive Review of the Literature

Poroid hidradenoma (PH) is a rare benign adnexal tumor of eccrine differentiation. It is the rarest of the four described variants of poroid neoplasms. PHs characteristically share a hybrid of the architectural features of the hidradenoma, namely, tumor cells are entirely intradermal with both solid and cystic components, and the cytologic characteristics of the poroid neoplasms, containing predominantly poroid and cuticular cells. Many published reports of PH since its original discovery in 1990 state that "very few" cases of PH can be found in the literature. Here, we have identified a total of 75 published accounts of PH, including the case presented here, as well as the associated patient demographics, lesion characteristics, treatment, and outcomes. We suggest that while uncommon, PH is likely not exceptionally rare and could be an underreported diagnosis.

Poroid hidradenocarcinoma and atypical hidradenoma papilliferum of the vulva – Two cases

Benign and malignant tumours may arise from eccrine and apocrine sweat glands. Hidradenocarcinoma is a rare malignant eccrine sweat gland tumour representing <0.01% of all skin cancers. There are 6 case reports in the literature of hidradenocarcinoma arising on the vulva, none of which are classified as poroid hidradenocarcinoma. Hidradenocarcinoma is thought to be an aggressive tumour with poor prognosis and high levels of local recurrence and systemic metastases. Conversely, hidradenoma papilliferum is a common benign apocrine sweat gland tumour found on the vulva. The prevalence and significance of atypical changes, however, is unknown. Distinguishing between these tumour types can be difficult. The authors present two cases, a poroid hidradenocarcinoma and an atypical hidradenoma papilliferum with necrosis and increased mitotic activity, to illustrate the diagnostic challenges associated with rare tumours of the vulva in the absence of an established histopathological classification system.