- Asymmetrical ;
Infiltrative growth pattern ;
smooth islands and small irregular shaped nests ;
- Focal necrosis (comedonecrosis)
types of atypical cells: eosinophilic and clear cells.
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 ;
structures ; Intracytoplasmic lumina formation ;
differentiation ; Melanin pigment is demonstrated in some cases ;
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.