http://www.histopathology-india.net/SwCa.htm

Cysts:

Hydrocystoma -Eccrine/Apocrine

Hamartomas:

Eccrine/Apocrine naevus

Eccrine Angiomatous Hamartoma

Porokeratotic eccrine ostial naevus

Benign Neoplasms:

Syringocystadenoma Papilliferum

Hidradenoma Papilliferum

Nipple Adenoma

Syringoma

Spiradenoma

Cylindroma

Chondroid Syringoma (benign mixed tumour)

Poroma

Hidradenoma

Apocrine adenoma

Papillary eccrine adenoma

Syringofibroadenoma

Eccrine porocarcinoma was first described by Pinkus and Mehergan as 'epidermotropic eccrine carcinoma' and probably represents the commonest form of sweat gland carcinoma.

Some tumours are of long duration suggesting malignant transformation of a poroma or hidroacanthoma simplex . Rarely some may arise from organoid nevus.

Age:  Predilection for older patients  

Site: Usually located on distal extremities.

Clinical presentation: Presents as a verrucous plaque  or polypoid growth.

Microscopic features:

Asymmetrical , infiltrative growth pattern  ;  Large smooth islands and small irregular shaped nests   ;  Focal necrosis (comedonecrosis) ;  2 types of atypical cells: eosinophilic and clear cells. Eosinophilic cells - polyhedral or fusiform with round to oval hyperchromatic nuclei, distinct nucleoli, indistinct cell boundaries, and a variable amount of cytoplasm (small eosinophilic cells or large eosinophilic cells);  Clear cells  -  large and polyhedral with round to oval nuclei, abundant clear cytoplasm, and distinct cell borders ; Clear cell areas are less prominent than hidradenocarcinoma  ; Ductal structures  ;  Intracytoplasmic lumina formation ; Squamous differentiation ; Melanin pigment is demonstrated in some cases ; Tumour shows multiple attachments to the epidermis ; Inflammatory infiltrate around neoplastic masses is composed of lymphocytes and plasma cells, rarely mixed with neutrophils and eosinophils ; Tumour with only intra- epidermal component is known as in-situ porocarcinoma ; Intraepidermal portion of the growth is composed of large atypical cells arranged in irregular nests and islands, variable in size and in shape, and sharply demarcated from the surrounding epidermal keratinocytes.

Benign component of poroma and hidroacanthoma simplex is present in about 10% of cases.

Neoplastic cells contain glycogen and intratubular, PAS-positive, diastase-resistant material is usually present.

Immunocytochemistry:  Tumour is cytokeratin , CEA and epithelial membrane antigen positive.

Local recurrence rate is lower than some low grade tumour. Metastasis to local lymphnode may be present in 10-20% of cases. Multiple cutaneous deposits and microscopic epidermotropic deposits may develop.

Dermatopathology Case Link  

Abstracts:

Porocarcinoma Arising in Pigmented Hidroacanthoma Simplex.Am J Dermatopathol. 2005 Dec;27(6):500-503.

Unusual case of porocarcinoma of the foot with no clinically evident dermatologic manifestations.J Foot Ankle Surg. 2005 Sep-Oct;44(5):412-4.

Porocarcinoma in a patient with chronic arsenism and multiple Bowen's disease: case report.Dermatol Surg. 2005 Sep;31(9 Pt 1):1149-51.

Eccrine porocarcinoma of the upper eyelid.Australas J Dermatol. 2005 Nov;46(4):278-81.

Malignant eccrine poroma.Saudi Med J. 2005 ;26(5):859-61.

Eccrine porocarcinoma (malignant eccrine poroma): a case report. 2005;Dermatol Online J. ;11(2):17.

Eccrine porocarcinoma with Bowenoid changes: epithelial membrane antigen is not a useful marker for malignant tumours arising from eccrine gland structures.Acta Derm Venereol. 2004;84(2):142-4.

Widespread metastatic eccrine porocarcinoma.J Am Acad Dermatol. 2003 Nov;49(5 Suppl):S252-4.

Eccrine sweat gland carcinoma of the skin.Pathologe. 2002 ;23(1):79-88.

Eccrine porocarcinoma with extensive cutaneous metastasis. Ann Dermatol Venereol. 2002 ;129(2):225-8

Aberrant expression of p16 and RB protein in eccrine porocarcinoma.J Cutan Pathol. 2002 Sep;29(8):473-9.

Malignant eccrine poroma in an unusual location.J Eur Acad Dermatol Venereol. 2002;16(6):631-3.

Unusual metastatic spread of a malignant eccrine poroma. 2002; Dermatology Online Journal 8(2): 7

Malignant eccrine poroma in an elderly African-American woman.Dermatol Surg. 1999 ;25(9): 733-5.

Malignant eccrine poroma with multiple visceral metastasis: report of a case with autopsy findings. J Cutan Pathol 1996;53:566-70.

Porocarcinoma of the heel. A case report with unusual histologic features.Cancer. 1996 ;78(4):751-7.

Metastasizing eccrine porocarcinoma: report of a case and review of the literature.J Am Acad Dermatol. 1996 Nov;35(5 Pt 2):860-4.

Clear cell eccrine carcinomas of the skin. A clinicopathologic study of nine patients.Cancer. 1994;73(6):1631-43.

Eccrine porocarcinoma. A review of 24 cases.Ann Dermatol Venereol. 1993;120(1):107-15.

Carcinoma of Sweat glands.  Pathol Annual. 1987: 22 (part1): 83-124.

Sweat gland carcinoma: A comprehensive review.  Semin Diagn Pathol. 1987 Feb; 4(1) : 38-74

Adnexal carcinomas of skin. Cancer. 1985 Sep1; 56(5) :1147-62 

Eccrine adenocarcinoma. A clinicopathologic study of 35 cases. Arch Dermatol. 1983;119 (2): 104-14.

Eccrine porocarcinoma: a case report with light microscopy and ultrastructure. Pathology.1982;14(4):469-75.

Carcinomas of Sweat Glands.