Basal cell carcinoma: differential diagnoses. Morphological criteria and major immunohistochemical findings
| Architecture | Cytology | 34βE12, p63 | PSA | S-100 protein, SMA | |
|---|---|---|---|---|---|
| PSA, prostate specific antigen; SMA, α smooth muscle actin. | |||||
| Basal cell carcinoma (adenoid cystic carcinoma) | Proliferation of cells arranged in various architectural patterns, showing morpho-logical criteria for malignancy (table 5) | Basaloid cells with large nuclei with considerable irregularity and variable size | + | ± | − |
| Poorly differentiated adenocarcinoma (mostly Gleason grade 5) | Tumour proliferation without glandular differentiation and composed of solid sheets, cords or single cells; necrosis can be present | Cells with enlarged nuclei and prominent nucleoli | − | + | − |
| Transitional cell (urothelial) carcinoma | Irregular solid nests and cords with a striking propensity for growth within ducts and acini | High nuclear grade with substantial nucleomegaly, nuclear pleomorphism, and nuclear hyperchromasia. Prominent nucleoli often present | + | − | − |
| Neuroendocrine carcinoma | Sheets of cells, with ribbons, nesting, palisading along fibrous bands, and rosette-like structures | Polygonal, round, or spindled tumour cells with scanty cytoplasm, and hyperchromatic nuclei identical to pulmonary small cell carcinoma | − | − | − |
| Basaloid carcinoma of the rectum | Solid tumour nests exhibiting peripheral palisading, sometimes with foci of mucin secretion and areas of squamous differentiation | Similar to cutaneous basal cell carcinoma | + | − | − |