Adenoid cystic and adenoid basal carcinoma of the uterine cervix - Comparative morphologic, mucin, and immunohistochemical profile of two rare neoplasms of putative 'reserve cell' origin

Adenoid cystic carcinomas (ACCs) and adenoid basal carcinomas (ABCs) are ra re neoplasms of the uterine cervix that are currently regarded as distinct clinicopathologic entities. Accurate distinction between ABCs and ACCs is o f clinical importance because of differences in their biological behavior. This study compares the morphologic, mucin, and immunohistochemical profile s of 18 cervical ACCs, 8 ABCs, and 1 combined ABC-ACC. Serial sections from the 27 cases were stained with hematoxylin and eosin, periodic acid-Schiff -diastase, mucicarmine, and alcian blue and subjected to a panel of immunop eroxidase markers, namely, MNF116, CAM 5.2, CK7, CK20, epithelial membrane antigen, carcinoembryonic antigen (CEA), S-100, HHF 35, laminin, and type T V collagen. One ACC was also examined ultrastructurally. Almost all patient s were postmenopausal black women. The distinction between ABC and ACC was best made morphologically. Divergent epithelial differentiation was seen in 18 cases (11 ACCs, 6 ABCs, and 1 ABC-ACC). Six cases with intact surface e pithelium showed a high grade squamous intraepithelial lesion. There was no significant difference in mucin staining. Both tumor types had a similar i mmunohistochemical profile, apart from type IV collagen and laminin stainin g, which occurred exclusively in relation to the extracellular basement mem brane-like material in the ACC, Eleven ACCs and three ABCs were S-100-posit ive, including the respective ACC and ABC components of the combined ABC-AC C. Eight of the S-100-positive neoplasms with ACC morphology also stained w ith HHF 35, suggesting myoepithelial differentiation. The latter was confir med in one ACC examined ultrastructurally. The similar clinical profiles, a part from the different biological behavior, capacity for divergent differe ntiation, and the occurrence of ABC areas in some ACCs and vice versa sugge st that these tumors may share a common histogenesis, forming part of a mor phologic and biologic spectrum of basaloid cervical neoplasms of putative " reserve cell" origin. Circumstantial evidence suggests that ABC may be a pr ecursor of cervical ACC.