Adenoid basal lesions of the uterine cervix: evolving terminology and clinicopathological concepts

Abstract

The epithelial proliferations that are designated adenoid basal carcinoma (ABC) in the current classification from the World Health Organization represent <1% of all cervical malignancies. These lesions may be associated, and occasionally show morphologic transitions with, conventional cervical malignancies. The determination of the precise frequency with which these so-called ABCs show this association is hampered by the inherent selection bias in the reported cases. However, this frequency appears to be substantial (>15%). The biologic course of ABCs that are associated with separate malignancies is largely dependent on the clinicopathologic parameters of the associated malignancies. Morphologically pure lesions, in contrast, have largely been associated with favorable patient outcomes, as none of the 66 reported patients have experienced tumor recurrence, metastases or tumor-associated death, irrespective of the modality of treatment. Although the finding of genome integrated high-risk human papillomavirus (HPV) types and p53 alterations in adenoid basal lesions (ABL) argue in support of their neoplastic nature, we identified no lines evidence that suggest an inherent malignancy for morphologically pure lesions. The finding of morphologic transitions between ABLs and conventional malignancies and shared HPV types in these areas, suggest that ABLs have some malignant potential. However, the precise magnitude of this potential is not readily quantifiable and should not dictate the management of morphologically pure lesions that are entirely evaluable. ABLs continue to occupy a unique position in human oncology in which the term carcinoma (without an in-situ suffix) is applied to a tumor that has not been shown to recur, metastasize or cause death. We concur with a previous proposal that the term ABC should be discarded and replaced with Adenoid Basal Epithelioma (ABE). In our opinion, there is insufficient evidence at present time to expose patients with morphologically pure lesions to the ominous implications--social, psychological, medical, financial--of a "carcinoma" diagnosis. Morphologically impure lesions should not be designated ABC or ABE. Furthermore, given the uncertainties regarding the frequency with which ABE are associated with separate malignancies, we suggest that the ABE designation only be applied when the tumor in question is entirely evaluable e.g in a hysterectomy specimen or in an excisional biopsy with negative margins. Otherwise, the generic designation Adenoid Basal Tumor is preferable. This approach strikes an appropriate balance between the need to prevent over-treatment of pure lesions on one hand, and the need to ensure that the lesions are indeed pure on the other.

Figure 1

Scanning magnification view of a pure adenoid basal lesion (adenoid basal epithelioma), showing an infiltrative proliferation of basaloid nests. (hematoxylin and eosin, original magnification 10×)

Figure 2

Intermediate power view of adenoid basal nests. Note the lack of any significant stromal reaction. (hematoxylin and eosin, original magnification 20×)

Figure 3

High power view of adenoid basal nests, each comprised of monomorphic, small cells with basaloid, round to oval nuclei, inconspicuous nucleoli and scant cytoplasms (hematoxylin and eosin, original magnification 60×).

Figure 4

Some adenoid basal nests may show prominent clear cell change due to accumulation of cytoplasmic glycogen in constituent cells. Basaloid cells are still evident at the periphery of this nest (lower field). (hematoxylin and eosin, original magnification 60×)

Figure 5

Small glandular or acinar structures such as is illustrated are not uncommonly found in adenoid basal lesions. (hematoxylin and eosin, original magnification 60×)

Figure 6

The luminal compartments of the gland-like structures may contain secretory material. (hematoxylin and eosin, original magnification 60×)

Figure 7

Small basement membrane-like material may be present in adenoid basal lesions. (hematoxylin and eosin, original magnification 40×)

Figure 8

Squamous metaplasia in an adenoid basal nest. Note the basaloid cells at the periphery of the nest. (hematoxylin and eosin, original magnification 60×)