Eccrine porocarcinoma was first described by Pinkus and Mehergan as 'epidermotropic
eccrine carcinoma' and probably represents the commonest form of sweat
Some tumours are of long duration suggesting malignant transformation of
. Rarely some may arise from organoid nevus.
Usually located on distal extremities.
Presents as a verrucous plaque or polypoid
infiltrative growth pattern ; Large
smooth islands and small irregular shaped nests ; Focal necrosis (comedonecrosis)
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 ;
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.
contain glycogen and intratubular, PAS-positive, diastase-resistant
material is usually present.
Tumour is cytokeratin , CEA and
epithelial membrane antigen positive.
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
Dermatopathology Case Link