DS18: Porocarcinoma: a case series of 41 patients diagnosed over a 12-year period

R. Applewaite,¹ F. Shah,¹ A. Martin-Clavijo² and P. Gazzani¹

¹University Hospitals Birmingham and ²University Hospitals Birmingham, Birmingham, UK

Porocarcinoma is a rare skin adnexal malignancy originating from sweat glands. The clinical course varies considerably, from in situ disease to a more aggressive form. We report a large case series of histologically confirmed porocarcinomas referred to our specialist skin cancer multidisciplinary team. Forty-one patients (20 males, 21 females) diagnosed with porocarcinoma over the last 12 years were identified. Twenty-two (54%) had lower limb disease (16 females and six males), seven (17%) had upper limb lesions (three females and four males), nine (22%) had head and neck lesions (two females and seven males) and three (7%) patients had lesions on their trunk (one female and two males). The age range of our patients was 56–90 years (average 77). Data on ethnicity were limited, but 24 were white British or white Irish, one was black African and one was black Caribbean. Twenty-one patients died (51%) of nonporocarcinoma causes within 9 years of diagnosis, with 14 (34%) dying within 2 years of diagnosis. Nine (22%) had a diagnosis of cancer, with seven of those having another cutaneous cancer. Only two (5%) patients were immunosuppressed – one after a renal transplant and one due to myasthenia gravis. Four patients had in situ disease only. Twenty-seven patients (66%) had surgery, eight (20%) had Mohs micrographic surgery (MMS), treatment could not be determined in three (7%), one (2%) died before treatment and one (2%) had a combination of palliative radiotherapy and hormonal therapy. Two of the patients treated with wide local excision had recurrent disease, and none of those treated with MMS had recurrence. Five (12%) had locoregional disease, three with intransit disease and two with lymph node involvement. No patient had distant disease identified. Our data compare with that previously published from smaller case series. Porocarcinoma is a disease predominantly of elderly people, often presenting (mainly in females) on the lower limb. Males were more likely to develop primary lesions on their head. The 5-year survival rate approaches 50%, likely reflecting the elderly population it affects. Locoregional metastasis occurred in 12%, with no distant organ involvement seen. There is some evidence that MMS is the best option to reduce local recurrence rates, and although our data support this, three times fewer patients were managed with MMS than with other surgery.