Endocervical type A (noncystic) tunnel clusters with cytologic atypia. A report of 14 cases.

Tunnel clusters (TCs) are benign, pseudoneoplastic glandular lesions of the cervix that may be divided into type A (noncystic) and type B (cystic). We report 14 examples of type A TC characterized by a florid proliferation of glands with greater cytologic atypia than normally encountered in this lesion. The majority had been sent for consultation to exclude adenoma malignum (minimal deviation adenocarcinoma). The patients ranged in age from 32 to 54 (mean 44.8) years. Mean gravidity was 2.5 and parity 2.1; all but one patient were multigravid. A history of recent exogenous hormone intake was present in 4 (33%) patients. All of the lesions were incidental findings, and none was associated with a gross abnormality. Microscopically, all were characterized by a lobulated proliferation of predominantly small-caliber, nondilated, closely packed glands frequently arranged around a central primary or secondary endocervical cleft. Most were well circumscribed, but irregular borders created a pseudoinvasive appearance in four cases. The lesions ranged from 2.5 to 7 (mean 3.5 mm) and were frequently associated with type B TC. The glands were lined by either mucinous columnar cells or low cuboidal cells. Cellular crowding with pseudostratification was common, but true stratification or cribriforming was absent. All cases had foci of cytologic atypia including nuclear enlargement, hyperchromasia, prominent nucleoli, and vesicular chromatin. Mitotic activity was absent or inconspicuous. Follow-up in 9 patients (7 treated with hysterectomy, one each with cone biopsy and biopsy only) ranged from 1 to 6 (mean 2.7) years and was uneventful in all of them. Follow-up was unavailable in one, and four were recent cases. Endocervical type A TC with cytologic atypia is a common benign glandular lesion that must be distinguished from adenoma malignum.