<unk>  (PCA) (also termed malignant poroma, eccrine<unk> , and malignant eccrine poroma) is a rare form of skin cancer that develops in eccrine sweat glands, i.e. the body's widely distributed major type of sweat glands, as opposed to the apocrine sweat glands which are located primarily in the armpits and perineal area. This cancer develops in individuals as a single cutaneous tumor in the apical part (termed the acrosyringium) of these sweat glands' ducts (i.e. channels) at or near to where they open on the skin's surface. PCA tumors are classified as one form of the cutaneous adnexal tumors; in a study of 2,205 cases, PCA was the most common (11.8%) form of these tumors.<unk> s are malignant counterparts to the far more common benign tumors of the eccrine sweat gland's acrosyringium, i.e. poromas. PCA tumors may arise from one of these longstanding poromas (in one study this occurred in 18% of cases) but more commonly appear to develop independently of any precursor poroma. PCA are locally invasive tumors that have been treated by surgical resection but often recur at the site of their surgical removal and metastasize to distant tissues before or after their removal. Repeatedly recurrent, unresectable, and metastatic PCA have been treated with chemotherapy and/or radiotherapy. However, metastatic PCA has responded poorly to these treatments and carries a poor prognosis. Because of their rarity and lack of distinct clinical features and variable physical and microscopic histological appearances, the diagnosis of<unk> s is often challenging. PCA has commonly been either mis-diagnosed or over-diagnosed. Under-diagnosis may have been responsible for a recent study conducted in a United Kingdom single center that reported that the number of PCA cases had increased 3-fold over the previous 4 years and was expected to rapidly rise further during the next decade.
Porocarcinoma
Poroma
Choriocarcinoma
Embryonal carcinoma
Embryoma
Polyembryoma
Seminoma
Leiomyosarcoma