| Japanese Journal of Clinical Oncology | Pages |
Introduction
Case Report
Pathological Findings
Discussion
References
Sclerosing Sweat Duct Carcinoma in the Peri-Anal Skin: a Case Report
We report a case of sclerosing sweat duct carcinoma, a rare tumor, occurring in the peri-anal skin, a rare position. The patient, a 41-year-old Japanese woman, was admitted to our hospital with recurrence of sclerosing sweat duct carcinoma in the peri-anal skin, which had been initially resected at a local hospital. She underwent abdomino-perineal resection. No lymph node metastases or distant metastases were found. Although we allowed a 2-cm resection margin around the tumor, microscopy showed that the tumor had extended to within 2 mm of this margin at several sites, indicating that sclerosing sweat duct carcinoma is locally aggressive. An ample resection margin should therefore be taken at initial surgery for this type of tumor. Moreover, surgical excision that is wider and deeper than primary excision is required when this tumor recurs.
INTRODUCTION
Sclerosing sweat duct carcinoma is believed to show both follicular and sweat gland differentiation and often mimics the histologic features of syringoma (1 ). This carcinoma is sometimes called malignant syringoma, syringoid eccrine carcinoma, syringomatous carcinoma or microcystic adnexal carcinoma. It is a rare adnexal tumor, and only 56 cases have been reported (2 -9 ). The face and axillary areas are most often involved. Only one case situated on the buttock has been reported (6 ). The most important clinical characteristic is a highly infiltrative growth pattern without lymphatic or distant metastasis. In 47% of patients with sclerosing sweat duct carcinoma, recurrences have been reported at the site of origin following primary excision (6 ). Here we report a rare case of sclerosing sweat duct carcinoma located on the peri-anal skin and describe the importance of wide resection.
CASE REPORT
A 41-year-old Japanese woman found a small mass at the right side of the anus in 1990. She visited a local hospital because of enlargement of the mass in October 1992, and the mass was excised. As the histopathological diagnosis was sclerosing sweat duct carcinoma and the surgical margin was positive, the patient was closely followed up at the hospital. The tumor was palpated again at the resection site in October 1994, and biopsies obtained from it confirmed the recurrence of sclerosing sweat duct carcinoma. The patient was therefore admitted to the National Cancer Center Hospital in February 1995 for removal of the recurrent tumor.
Physical examination showed that the tumor was located in the skin to the right of the anus, beneath the scar left by the initial excision. The tumor appeared as a solitary, firm mass, measuring 6 * 4 cm. Although the tumor seemed to invade the surrounding subcutaneous tissue, the overlying skin was smooth except for the scar. It was suspected that the external sphincter muscle had been invaded by the tumor, and lymph node swelling was detected in the bilateral inguinal areas. Laboratory studies revealed slightly increased levels of serum carbohydrated antigen 19-9 (CA19-9) and squamous cell carcinoma. Magnetic resonance imaging detected the tumor as an indistinct nodule which was suspected of infiltrating the anal sphincter. Transrectal ultrasonography revealed the tumor as a low-echoic mass, also with probable sphincter muscle invasion. However, CT scanning was unable to detect the tumor. Therefore abdomino- perineal resection with wide removal of the posterior wall of the vagina and soft tissues in the buttock was performed (Fig. 1 ). For the perineal approach, the incision line was made 2 cm around the tumor to allow a sufficient surgical margin. The swollen lymph nodes in the bilateral inguinal areas and the right external iliac artery were removed. None of them showed microscopically evident metastasis. Systematic lymph node dissection in the inguinal region was not performed.
DISCUSSION
Sclerosing sweat duct carcinoma is a rare tumor, and only 33 cases treated by surgical excision have been reported (2 -8 ). Abenoza and Ackerman (9 ) reported another 23 cases as well differentiated syringomatous carcinomas, which were included in biopsy specimens of skin. Most of them were situated on the face (87%), and the remainder in the axillae and on the scalp. Only one case involved the buttock (6 ). The present case is therefore the second case to be located in the buttock region.
The most characteristic microscopic feature of sclerosing sweat duct carcinoma is a highly infiltrative growth pattern (1 ). The tumor infiltrates the surrounding tissues, forming small nests, thin cords, ductular structures and small keratin-filled cysts with a dense fibrotic stroma (1 ). Perineural invasion is frequently observed (1 ). In the present case, the neoplasm infiltrated extensively into the surrounding subcutaneous tissue and striated muscle, and in some areas perineural invasion was seen. The tumor cells showed minimal cytologic atypia and few mitotic figures. The recurrent tumor showed histological features similar to those of the primary tumor.
Cooper et al. (6 ) reported that 7 of 15 patients with sclerosing sweat duct carcinoma had recurrences after surgery. These recurrences developed after long disease-free intervals of up to 24 years. In the present case, there was also a history of slow tumor growth.
Abdomino-perineal resection was selected to increase the likelihood of regional curability, and macroscopically a free margin of more than 2 cm was taken. However, microscopy showed that the tumor had infiltrated to within 2 mm of the margin at several sites. This shows that sclerosing sweat duct carcinoma is a locally aggressive tumor, and therefore wide surgical excision with sufficient lateral and deep margins is needed for complete curative resection.
Lymph node involvement has been documented in only one previous case of this tumor (6 ). However, this case seemed to show direct extension from the primary site into a subjacent lymph node, rather than lymphatic spread, and distant metastasis was not observed. In the present case, no lymph node or distant metastases were detected. Therefore, lymphadenectomy is not required for treatment of this tumor.
In cases of recurrent tumor like the present one, it may be quite difficult to decide the range of resection required because the tumor margin is very unclear. The surgical margins should therefore be evaluated very carefully by intraoperative pathological examination. However, the margins may sometimes be unreliable, since this tumor is characterized by dispersed and discontinuous growth (6 ). Furthermore, in one of the previous cases of sclerosing sweat duct carcinoma, the recurrent tumor was reported as showing increased cytologic atypia (6 ). Accordingly, surgical excision of a recurrent tumor of this type should be wider and deeper than for primary excision, because of the tumor's highly infiltrative growth pattern.
References
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Copyright© Japanese Journal of Clinical Oncology, 1997.
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