Table 1.
Differential diagnosis of Endocrine mucin producing sweat gland carcinoma (EMPSGC)
| Differential diagnosis | Morphological features | IHC | Molecular alterations |
|---|---|---|---|
| EMPSGC | Variably cystic tumor with cribriform, solid, papillary architecture; small cells with uniform nuclei, “salt and pepper” chromatin; rosettes; variable intracellular, extracellular mucin | Positive for CK, CK7, ER, PR, AR, neuroendocrine markers; myoepithelial markers (p63, p40, SMA) partly retained at periphery of tumor nodules | No diagnostic molecular alteration |
| Adenoid cystic carcinoma, solid type | Solid sheets of basaloid cells with scant cytoplasm, angulated hyperchromatic nuclei; scarce ductal cells | SOX 10 positive; CK7, CD117 in ductal cells; p40, SMA in myoepithelial cells; Myb protein overexpression may be present | MYB, MYBL1 gene rearrangements |
| Basal cell adenocarcinoma | Biphasic tumor with jigsaw puzzle- like solid nests; dark and pale cells; peripheral palisading; hyaline basal lamina material may be present around tumor islands | CK, myoepithelial markers (p40, p63, SMA) positive; nuclear β-catenin may be present; negative for neuroendocrine markers | No diagnostic molecular alteration |
| NUT carcinoma | Monomorphic basaloid cells with scant cytoplasm, prominent nucleoli; abrupt squamous differentiation; necrosis, frequent mitoses | Positive for NUT protein (speckled staining), p63, p40; neuroendocrine markers are negative or focal faint positive | NUTM1 gene rearrangements |
| Adamantinoma-like Ewing sarcoma | Sheets, nests, lobules of basaloid cells; variably myxoid to hyalinized stroma; keratinization, squamous pearls; rosettes, peripheral palisading of nuclei, basement membrane material; necrosis, frequent mitoses | Diffuse CD99, NKX2.2, CK, p63 and p40 positivity; neuroendocrine markers may be positive; negative for hormone receptors | EWSR1-FLI1 gene fusion |
| Metastases from basal cell carcinoma | Basaloid cells with peripheral palisading; retraction spaces around tumor islands; frequent apoptosis | BER-EP4 positive; negative for neuroendocrine markers, hormone receptors | No diagnostic molecular alteration |
AR androgen receptor, CK cytokeratin, ER estrogen receptor, PR progesterone receptor, SMA smooth muscle actin