Salivary glands

Primary salivary gland neoplasms

Malignant

Basal cell adenocarcinoma



Last author update: 13 January 2022
Last staff update: 13 January 2022

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PubMed Search: Basal cell adenocarcinoma[TI] salivary

Natasha Prosser, B.Sc., M.B.B.S.
Ruta Gupta, M.D.
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Cite this page: Prosser N, Gupta R. Basal cell adenocarcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/salivaryglandsbasalcelladenocarcinoma.html. Accessed December 6th, 2022.
Definition / general
Essential features
  • Biphasic, low grade malignancy of salivary gland
  • Parotid is the most common location; rare in other salivary glands and minor salivary gland tissue
  • Histologic features similar to basal cell adenoma but with evidence of invasive growth pattern
  • Diagnosis based on demonstration of a dual cell population of centrally located ductal cells and abluminal basal cells with peripheral palisading of nuclei
  • Squamous and sebaceous differentiation may be seen
  • Surgery with clear margins is the mainstay of treatment
Terminology
  • Basal cell adenocarcinoma (BCAC)
  • Use of other terminology is not recommended
ICD coding
  • ICD-O: 8147/3 - basal cell adenocarcinoma
Epidemiology
  • Rare primary salivary gland tumor, accounting for < 1 - 2% of salivary gland malignancies
  • Wide age range (40 - 90)
  • Most frequent in adults in seventh to eighth decade; exceedingly rare in children
  • Slight female predominance (F:M = 1.2:1) (Surg Pathol Clin 2021;14:25)
Sites
  • Parotid (75 - 90%), submandibular, minor salivary gland of oral cavity
Etiology
  • Arises from pluripotential, ductal and myoepithelial cells
  • Majority arise de novo; approximately 25% of cases arise from basal cell adenoma (Cancer 1996;78:2471)
  • Rare examples may occur in the context of familial cylindromatosis syndromes, such as Brooke-Spiegler syndrome (Surg Pathol Clin 2021;14:25)
Clinical features
Diagnosis
  • Imaging modalities for workup of salivary gland neoplasms include ultrasonography, CT and MRI (Otolaryngol Head Neck Surg 2021;164:27)
  • Cytologic diagnosis exceedingly difficult due to morphologic overlap with other more common biphasic salivary gland neoplasms, including pleomorphic adenoma and adenoid cystic carcinoma (Diagn Pathol 2013;8:171)
Radiology description
  • No specific radiological findings
Prognostic factors
Case reports
Treatment
Gross description
Gross images

Contributed by Natasha Prosser, B.Sc., M.B.B.S.

Parotid gland tumor



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Bisected specimen with focal hemorrhage

Frozen section description
  • Should not be used; diagnosis may not be possible on frozen section
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Natasha Prosser, B.Sc., M.B.B.S. and Ruta Gupta, M.D.

Peripheral palisading

Biphasic tumor composition

Solid pattern

Tubular and trabecular growth patterns

Membranous pattern


Glandular elements

Squamous morules

Invasion


Perineural invasion

DPAS special stain

Beta catenin IHC

Cytokeratin 7 IHC

p63 IHC

Ki67 IHC

Cytology description
Positive stains
Electron microscopy description
  • Not used in routine practice
  • Ultrastructural features identical for basal cell adenoma and BCAC
  • Cells show basal, myoepithelial and ductal differentiation
  • Excess basal lamina, marginally and intercellularly seen around nonluminal cells
  • Reference: Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:485
Molecular / cytogenetics description
Sample pathology report
  • Left superficial parotid, excision:
    • Basal cell adenocarcinoma (see comment)
    • Comment: The sections show a partly encapsulated tumor composed of anastomosing tubules and ductules with a prominent hyaline stroma. In most areas, there appears to be a double cell layer, with CK7 positive pale cells surrounded by SMA positive darker cells abutting the hyaline stroma. There is invasion of adipose tissue with an extension close to the parotid gland. No perineural invasion was found. The tumor is 0.8 mm from the nearest inked margin of excision. Mitoses are sparse.
Differential diagnosis
  • Basal cell adenoma:
    • Well circumscribed, no invasion / infiltration into adjacent tissues
    • Multifocal or membranous type can simulate invasion
    • Nuclear beta catenin+
  • Pleomorphic adenoma:
    • Presence of myxoid / chondromyxoid matrix
    • Plasmacytoid and spindled cells frequent
    • Epithelial / myoepithelial cells blend into stroma; BCAC has abrupt border with matrix
    • Multinodular growth may simulate invasion
  • Canalicular adenoma:
    • May be multifocal but nearly always involves upper lip / minor salivary gland
    • Beaded chains of short columnar cells
    • No basement membrane material
    • S100+, SOX10+, GFAP+ (only at periphery)
    • p63-, actin-
  • Adenoid cystic carcinoma:
    • Cribriform patterns and punched out spaces surrounded by small cells with minimal cytoplasm
    • Palisading not prominent
    • Lacks large pale and small dark cells common in BCAC
    • Coarse nuclear chromatin, high mitotic rate
    • Of note: basal cell adenocarcinoma may occasionally show MYB overexpression (J Oral Pathol Med 2017;46:798)
  • Basaloid squamous cell carcinoma:
    • High grade neoplasm, usually oral or sinonasal tract rather than salivary glands
    • Basaloid, comedonecrosis and hyaline type material seen in both
    • Abrupt squamous differentiation
  • Polymorphous adenocarcinoma:
    • Occurs in minor salivary glands only
    • Polymorphous architectural patterns
    • Monotonous population of single cell type neoplastic proliferation
    • Cells have open, vesicular nuclear chromatin with small nucleoli (not basaloid cells)
    • Perineural invasion
    • Immunohistochemistry highlights only single cell population (not biphasic)
  • Skin basal cell carcinoma:
    • Skin tumors may metastasize to intraparotid lymph nodes or directly invade parotid
    • Palisading, basaloid architecture, necrosis and increased mitotic figures
    • Lacks biphasic appearance and myoepithelial cells
    • BerEP4+
Board review style question #1

A 70 year old man presents with a slow growing, painless lesion in the parotid. On gross examination, the lesion is well circumscribed, with a cream, partly cystic lesion. Which of the following is correct?

  1. Cytology is helpful in the diagnosis of this lesion
  2. Invasion distinguishes this lesion from its benign counterpart
  3. Molecular features are often used to differentiate this tumor from mimics
  4. This low grade neoplasm frequently metastasizes to the lung
Board review style answer #1
B. Invasion distinguishes this lesion from its benign counterpart. The tumor is a basal cell adenocarcinoma, a rare, indolent malignant counterpart to basal cell adenoma. Evidence of invasion is essential for diagnosis.

Comment Here

Reference: Basal cell adenocarcinoma
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