Junya Iwasaki1,2, Yuichi Yoshida2, Osamu Yamamoto2 and Shingo Tajima1
1Division of Dermatology, Department of Medicine of Sensory and Motor Organ, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago 683-8504, Japan and 2Department of Dermatology, National Defense Medical College, Japan. E-mail; firstname.lastname@example.org
Accepted July 3, 2007.
Poroma is a benign cutaneous neoplasm that usually occurs in middle-aged or elderly individuals as a solitary, reddish-pink nodule, appearing preferentially on the palms or soles (1). We report here a rare case of poroma of the eyelid.
A 91-year-old Japanese man presented at our hospital with a painless slow-growing, small nodule on his right lower eyelid of 1-year duration. The nodule was well-circumscribed, centrally ulcerative, reddish-pink and 4×5 mm in size (Fig. 1). He had no history of trauma or insect bite. The lesion was suspected to be a basal cell carcinoma. However, dermoscopic examination revealed pink to whitish, irregularly shaped structures composed of telangiectasia, fine hairpin-like vessels and some linear vessels (Fig. 2). There were no dermoscopic findings suggestive of basal cell carcinoma (2).
Fig. 1. Reddish-pink papule on the right lower eyelid.
Fig. 2. Dermoscopic findings of pink to whitish, irregularly shaped structures composed of telangiectasia, fine hairpin-like vessels and some linear vessels (original magnification ×10).
Histopathologically, the lesion consisted of well-defined nests of monomorphous cuboidal poroid cells with oval nuclei and eosinophilic cytoplasms connected with the overlying epidermis (Fig. 3a). Tubular structures and cystic spaces were also present. In addition, sebaceous components were observed within the tumour nests (Fig. 3b). No atypical mitotic figures were encountered. Based on these findings, a diagnosis of poroma with sebaceous differentiation was made.
Fig. 3. Histopathology of a punch biopsy specimen of the lesion. (a) The tumour consisted of well-defined nests of monomorphous cuboidal poroid cells (H&E ×40). (b) Sebaceous components were observed within the tumour nests (H&E ×400).
Poroma is a fairly common, slow-growing solitary adnexal tumour in association with the intra-epidermal portion of eccrine sweat ducts and has been classified traditionally as an eccrine neoplasm. However, poroma arising in the eyelid, as our case is extremely rare. To our knowledge, only 2 cases have been reported previously (3, 4). Moreover, in our case, sebaceous components were observed intermingled with poroid cells histopathologically. It is known that some cutaneous neoplasms can exhibit follicular, sebaceous, and sudoriferous differentiation because of the embryological association of these structures (so-called folliculo-sebaceous-apocrine unit). Sebaceous differentiation is not generally observed in eccrine poroma, since eccrine sweat glands arise from a distinct epithelial unit (1). Accordingly, Zaim (5) reported 3 cases of adnexal tumours differentiating toward both sebaceous and apocrine glands as sebocrine adenoma (5). On the other hand, some authors described eccrine poroma-like neoplasms with sebaceous elements as apocrine poroma with sebaceous differentiation (6, 7). It is interesting that those cases involved the face, body and extremities, but not the soles and palms. Our case is almost identical to these. Although there are meibomian glands in the eyelid, it is not possible to determine the exact origin of this neoplasm. However, we believe that it at least represents a separate pathological entity because it differs histopathologically from sebaceoma and sebaceous carcinoma. Most cells in our case are poroma cells and lack nuclear atypia, invasive, asymmetric growth patterns.
With regard to the dermoscopic findings of poroma, Altamura et al. (8) have recently reported polymorphous vascular patterns in eccrine poroma, as seen in our case. Clinically our case has a close resemblance to basal cell carcinoma. However the possibility is deniable based on the dermoscopic findings as well as the histopathologic findings. Basal cell carcinoma usually shows arborizing vessels rather than fine hairpin-like vessels as in our case in dermoscopy (9).
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