stained slides shows a biphasic glandular proliferation with inner apocrine cells and basal myoepithelial cells, separated by fibrous connective tissue stroma. The tumors are usually small, with a mean size of about 1.2 cm. • Ceruminous syringocystadenoma papilliferum All of the tumors are unencapsulated, but are usually well defined or circumscribed. The overlying surface epithelium is not involved. The tumor shows a dual or biphasic appearance, with glandular or cystic spaces showing inner luminal secretory cells with abundant granular, eosinophilic cytoplasm subtended by basal,
myoepithelial cells at the periphery, adjacent to the
basement membrane. The luminal cells will often have decapitation (
apocrine) secretions and will also have yellow-brown, ceroid,
lipofuscin-like (cerumen) pigment granules. There is no pleomorphic, limited
mitoses, and no
necrosis.
Immunohistochemistry can be performed to confirm the biphasic nature of the tumor. All cells are positive with
pancytokeratin and
epithelial membrane antigen; only the luminal
cells are positive with
CK7; only the basal cells are positive with
CK5/6,
p63,
S100 protein.
CD117 can be positive in either population. The cells are negative with
chromogranin,
synaptophysin and
CK20. == Diagnosis ==