A Poroid Neoplasia Arising Close to a Seborrheic Keratosis and a Trichoepithelioma

Abstract

A 69-year-old woman had a well-defined, slightly raised, brownish, keratotic plaque with an eccentric group of roughly circular, bluish, dome nodules on her right scapular area. Histological study revealed the presence of an eccrine poroma demonstrating features of eccrine poroma, hidroacanthoma simplex, and dermal duct tumor and arising in a lesion of seborrheic keratosis and a trichoepithelioma. In the eccrine poroma region, an area with malignant changes was evident. The findings in this case support the view of eccrine poroma as a spectrum of histological variants and the possibility of malignant transformation from a eccrine poroma towards porocarcinoma. The association with seborrheic keratosis is most probably coincidental, and the trichoepithelioma was probably due to induction of the tumoral stroma on adjacent follicular epithelia.

Eccrine porocarcinoma and Bowen's disease arising in a seborrhoeic keratosis

“…In this case, a small nodular lesion composed of BD and eccrine porocarcinoma appeared within a pre‐existing elevated macular SK lesion. Several types of malignant neoplasms arising in SK have been reported in the literature 3,5–9 . Most of these malignant tumours are basal cell carcinomas.…”

“…Most of these malignant tumours are basal cell carcinomas. Some cases of BD and malignant sweat‐gland tumours have been reported 5–9 . It is controversial whether malignant neoplasms arising in SK occur only by chance or if pre‐existing SK plays a particular role in the pathogenesis of the malignant neoplasms.…”

Bowen's disease with invasive adnexal carcinoma: The pluripotential nature of Bowen's disease cells

“…It has been suggested that BD most likely originates from germinal cells of the pilary outer root sheath and the pluripotential epidermal cells of the acrotrichium. 14,15,16 However, generation of eccrine porocarcinoma as seen in our case 1 and 3 may suggest that there is a type of BD-CA originating from more pluripotential epidermal cells other than germinal cells of the pilary outer root sheath. This notion can be substantiated by the various types of histological differentiation seen in BD-CA.…”

Carcinoma with eccrine differentiation arising in a seborrhoeic keratosis

“…Most of them were basal cell epitheliomas (BCEs) and in situ squamous cell carcinomas (SCCs) 1–3 . Infiltrating SCCs, and two cases of eccrine poroma with areas of malignant changes, have also been described 4–7 . To our knowledge, an overtly malignant carcinoma showing sweat gland differentiation has not yet been described in association with SK.…”