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Adenoid basal carcinoma

Authors: Peace A. Preston, B.A., Stephanie L. Skala, M.D.

Editorial Board Member: David B. Chapel, M.D.

Deputy Editor-in-Chief: Gulisa Turashvili, M.D., Ph.D.

Last author update: 26 November 2024

Last staff update: 26 November 2024

Copyright: 2003-2024, PathologyOutlines.com, Inc.

PubMed Search: Adenoid basal carcinoma cervix

Table of Contents

Cite this page: Preston PA, Skala SL. Adenoid basal carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cervixadenoidbasal.html. Accessed December 22nd, 2024.

Definition / general

Epithelial tumor composed of small, basaloid cells forming nests or cords
It typically has an infiltrative growth pattern, although desmoplasia should not be present (Am J Surg Pathol 1988;12:134, Arch Pathol Lab Med 2021;145:891)

Essential features

Nests of basaloid cells with low grade features
No desmoplastic stromal response
Associated with high risk human papillomavirus (HPV)
p16 block positivity
No known metastatic potential when occurring in pure form

Terminology

Adenoid basal epithelioma, low grade adenoid basal tumor (Oncol Rep 2019;41:1769)

ICD coding

ICD-O: 8098/3 - adenoid basal carcinoma
ICD-11: 2C77.1 & XH70J2 - adenocarcinoma of cervix uteri & adenoid basal carcinoma

Epidemiology

This lesion occurs most frequently in postmenopausal women (mean: 64.6 years); however, the lesion has been reported in patients as young as 20 years old (Oncol Rep 2019;41:1769, Hum Pathol 2005;36:82, Int J Gynecol Pathol 2002;21:327, Diagn Pathol 2006;1:20)
In studies with HPV PCR results, the vast majority of cases are positive for high risk HPV, most commonly HPV 16 (Hum Pathol 2005;36:82, Int J Gynecol Pathol 1997;16:301, Hum Pathol 2000;31:740)
The vast majority of reported invasive adenoid basal carcinomas (as opposed to low grade noninvasive adenoid basal tumors or adenoid basal hyperplasia) are positive for p16 and high risk HPV ISH (Hum Pathol 2012;43:2255, Int J Gynecol Pathol 2016;35:82)

Sites

Cervix, usually transformation zone, similar to other high risk HPV related lesions

Pathophysiology

Typically associated with, although not arising from, high grade squamous intraepithelial lesion (HSIL)
There has been speculation that basal cell hyperplasia may be a precursor lesion (Obstet Gynecol 1971;37:807, Int J Gynecol Pathol 2002;21:327)
Theorized to arise from cervical reserve cells (Am J Surg Pathol 1999;23:448, Int J Gynecol Pathol 2002;21:327, Int J Gynecol Pathol 2016;35:82)
Newer theories suggest origin from the Skene gland (female counterpart of prostate glands) (Am J Surg Pathol 2024;48:238, Pathology 2021;53:193, Int J Gynecol Pathol 2021;40:400)

Etiology

Infection with high risk HPV

Clinical features

These lesions are typically found incidentally and do not manifest grossly or clinically unless associated with another, more aggressive tumor (Arch Pathol Lab Med 2021;145:891)

Diagnosis

Microscopic examination of biopsy, loop electrosurgical excision procedure (LEEP) / cone or hysterectomy
- Pure adenoid basal carcinoma can only be definitively diagnosed in a well sampled excision specimen with negative margins
- In reports for biopsies, it is prudent to include a comment noting that this morphology sometimes co-occurs with other forms of invasive carcinoma (affecting prognosis)

Prognostic factors

In its pure form, adenoid basal carcinoma does not metastasize and has an excellent prognosis
Excision is typically curative (Arch Pathol Lab Med 2021;145:891)
When coexisting with other neoplasms, the prognosis is expected to be that of the more aggressive tumor type (Arch Pathol Lab Med 2021;145:891)

Case reports

20 year old woman with HSIL and incidental finding on subsequent LEEP specimen (Diagn Pathol 2006;1:20)
22 year old woman with HSIL and incidental finding on subsequent LEEP specimen (J Menopausal Med 2013;19:154)
54 year old woman with postmenopausal abnormal uterine bleeding (Balkan Med J 2012;29:453)
80 year old woman with uterine prolapse and an incidental finding in the cervix (Int J Clin Exp Pathol 2018;11:1758)

Treatment

Excision is curative

Gross description

Typically, grossly unremarkable unless associated with another neoplasm

Microscopic (histologic) description

Generally accepted features of pure adenoid basal carcinoma include absent to minimal mitotic activity, infrequent necrosis and a low degree of cytologic atypia (Arch Pathol Lab Med 2021;145:891)
~15% are present as a component of a mixed invasive tumor (Diagn Pathol 2006;1:18)
Per the 5th edition of the WHO classification of tumors
- Essential
  - Non-mass forming lesion
  - Infiltrative small nests or cords of morphologically bland basaloid cells
  - Absence of stromal reaction
- Desirable: p16 or HPV determination
Infiltrative nests or cords of cytologically bland, basophilic cells with minimal cytoplasm
Nests may display peripheral palisading, like other basaloid tumors
May have central squamous differentiation, cystic change, clear cell change
Deepest point of invasion is typically < 1 cm
No desmoplastic stromal reaction
Adenoid basal carcinoma is associated with HSIL in > 90% of cases or may be associated with another type of invasive carcinoma (in which case it should be called mixed carcinoma, with a comment on the additional components present and their relative percentages) (Hum Pathol 2012;43:2255, Hum Pathol 2005;36:82, Int J Gynecol Pathol 2016;35:82)

Microscopic (histologic) images

Contributed by Stephanie L. Skala, M.D.

Central squamous differentiation

Peripheral palisading

Cytoplasmic clearing

p16 block positivity

Cytology description

While these lesions are seldom diagnosed with cervicovaginal cytology, they have been described as sheets of small, hyperchromatic cells with oval nuclei, fine chromatin and indistinct nucleoli (J Pathol Transl Med 2015;49:396, Diagn Cytopathol 1996;14:172)

Cytology images

Images hosted on other servers:

Clusters of bland cells with peripheral palisading

Positive stains

p16: block positivity
p63: positive in basaloid cells
NKX3.1: glandular components show at least focal nuclear staining (Am J Surg Pathol 2024;48:238, Pathology 2021;53:193, Int J Gynecol Pathol 2021;40:400)
References: Diagn Pathol 2006;1:18, Hum Pathol 2012;43:2255, Hum Pathol 2005;36:82, Int J Gynecol Pathol 2016;35:82

Negative stains

CD117 (Int J Gynecol Pathol 2012;31:25)
CK17: negative in central areas of squamous metaplasia (J Low Genit Tract Dis 2019;23:77)

Molecular / cytogenetics description

Studies have employed various methodologies to detect high risk HPV, including RNA in situ hybridization (ISH), DNA ISH and polymerase chain reaction (PCR) (Am J Surg Pathol 1999;23:448, Hum Pathol 2005;36:82, Int J Gynecol Pathol 2016;35:82)

Sample pathology report

Cervix, loop electrosurgical excision procedure (LEEP):
- Adenoid basal carcinoma (0.8 cm), arising in association with high grade squamous intraepithelial lesion (CIN 3); margins negative (see comment)
- Comment: The adenoid basal carcinoma in this specimen is seen in its pure form, with no features of a more aggressive tumor type. Adenoid basal carcinoma has no known metastatic potential when occurring in its pure form.

Differential diagnosis

Squamous cell carcinoma - basaloid and well differentiated (Arch Pathol Lab Med 2021;145:891):
- Desmoplastic stromal response may be seen
- Higher degree of mitotic activity
- More frequent necrosis
- Often positive for CK17
Adenoid basal hyperplasia / basal cell hyperplasia (Arch Pathol Lab Med 2021;145:891):
- Nests of basaloid cells attached to the superficial epithelium
- Deepest point of extension typically < 1 mm
- Negative for p16 and high risk HPV
Adenoid cystic carcinoma (Oncol Rep 2019;41:1769, Int J Gynecol Pathol 2012;31:25):
- Not currently listed as a distinct entity in the WHO classification for tumors of the cervix
- Significantly worse prognosis
- More likely to be symptomatic
- Larger cellular nodules, often with cribriform sieve-like pattern
- More nuclear atypia with more frequent mitoses and possible comedonecrosis
- Positive for CD117
- Negative for p16 when present as pure adenoid cystic carcinoma (Am J Surg Pathol 2016;40:529)
- Adenoid cystic morphology is often seen admixed with adenoid basal carcinoma, squamous cell carcinoma or small cell carcinoma; in these cases, p16 and high risk HPV are positive (Am J Surg Pathol 2016;40:529)
- May be prudent to reserve definitive diagnosis of cervical adenoid cystic carcinoma for tumors with MYB fusion
Ectopic prostate tissue (prostatic metaplasia):
- Prostatic type tissue can be seen in the cervix, usually within the stroma
- Glands with morphology and immunoprofile of prostatic glands, surrounded by basal cells
- Squamous metaplasia is often extensive, compressing and obscuring glands
- Not associated with HPV or block positivity for p16

Additional references

WHO Classification of Tumours Editorial Board: Female Genital Tumours, 5th Edition, 2020

Board review style question #1

Which of the following viruses or virus strains is most strongly associated with adenoid basal carcinoma of the cervix?

Epstein-Barr virus (EBV)
Human immunodeficiency virus (HIV)
Human papillomavirus (HPV) 11
Human papillomavirus (HPV) 16

Board review style answer #1

D. Human papillomavirus (HPV) 16. HPV 16 is a high risk strain of HPV and is the most common high risk strain identified in cases of adenoid basal carcinoma of the cervix. Answer A is incorrect because Epstein-Barr virus (EBV) is not associated with adenoid basal carcinoma of the cervix, nor is it associated with other gynecologic tumors. Rather, EBV is associated with nasopharyngeal and gastric carcinomas as well as several types of lymphoma (J Cancer Res Clin Oncol 2022;148:31). Answer C is incorrect because HPV 11 is a low risk strain of HPV and is one of the strains most associated with genital warts. It is not known to be associated with malignancies (Arch Gynecol Obstet 2012;286:1261). Answer B is incorrect because HIV is not associated with adenoid basal carcinoma. Individuals with HIV are at a greater risk for infection with high risk HPV and subsequent development of high grade squamous intraepithelial lesions (HSIL) and HSIL is commonly associated with adenoid basal carcinoma; however, there is currently no evidence to suggest that infection with HIV is directly associated with development of adenoid basal carcinoma (N Engl J Med 2018;378:1029).

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Reference: Adenoid basal carcinoma

Board review style question #2

The finding shown above is seen in a cervical loop electrosurgical excision procedure (LEEP) specimen from a 50 year old woman. What is the expected clinical course after complete excision?

Benign outcome
Local recurrence
Metastasis to pelvic lymph nodes
Progression to invasive squamous cell carcinoma

Board review style answer #2

A. Benign outcome. Adenoid basal carcinoma, in its pure form, has no known metastatic potential and has excellent prognosis. Answers B, C and D are incorrect because pure adenoid basal carcinoma has an excellent prognosis and complete excision is curative.

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Reference: Adenoid basal carcinoma

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