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Pathology Quiz Case 1: Diagnosis

Pathology Quiz Case 1: Diagnosis Diagnosis: Basal cell adenocarcinoma (BCAC) BCAC is a rare salivary gland cancer that was largely undefined until the early 1990s, when it was first incorporated into the World Health Organization's Histological Typing of Salivary Gland Tumors.1Before acquiring a unique identity, BCAC had been reported under several names, including basaloid salivary carcinoma, carcinoma ex monomorphic adenoma, malignant basal cell adenoma, and malignant basal cell tumor.2BCAC is a low-grade malignant neoplasm and the malignant counterpart of basal cell adenoma. It presents at a mean age of 60 years and exhibits no sex predilection.2-4Incidence estimates range from 0.6% of major salivary gland tumors to 1.6% of all salivary neoplasms.2,3Most cases arise de novo, with only 23% representing malignant transformation of a basal cell adenoma.4,5Nine out of 10 BCACs involve the parotid gland, but rare examples have been identified in the submandibular gland, sublingual gland, buccal mucosa, lip, tongue, nasal cavity, sinuses, and lacrimal gland.4,6-8 The microscopic appearance of BCAC features 2 populations of basaloid cells: (1) small darkly staining cells with sparse cytoplasm and basophilic nuclei, and (2) large lightly staining polygonal cells with more prominent cytoplasm, pale nuclei, and central eccentric nucleoli. The basaloid cells exist in variable ratios and organize themselves into 4 patterns: solid, membranous, trabecular, and tubular. The solid variant is most common and exhibits tumor nests separated by intervening collagenous stroma, as in this case. In cases in which multiple architectural patterns exist within a single tumor, classification is based on the most predominant configuration.4,5Very limited data suggest that the solid variant is more likely to exhibit perineural growth, intravascular growth, and metastastatic dissemination, although the prognostic value of this histologic subtype remains to be shown.2,4 BCAC rarely exhibits cellular pleomorphism, but occasional mitotic figures and small areas of necrosis may be observed.4,5,8Vascular or perineural invasion occurs in 25% of cases.8The basaloid cells display both epithelial and myoepithelial phenotypes, and their immunohistochemical profiles show variable reactivity for cytokeratin, carcinoembryonic antigen, epithelial membrane antigen, S-100 protein, smooth-muscle actin, and vimentin.4,7Although the genetic properties of BCAC are still poorly defined, many of these tumors express p53, bcl-2, and epithelial growth factor receptor.3,9As many as 10% to 14% of individuals with BCAC develop synchronous cutaneous lesions such as eccrine cylindroma, trichoepithelioma, or eccrine spiradenoma; this “skin-salivary gland tumor diathesis” suggests a common genetic origin that remains to be investigated.4,5,10 BCAC and basal cell adenoma possess very similar cell populations, and these 2 entities are often indistinguishable based on cytologic features alone.1A diagnosis of BCAC requires invasion into adjacent structures such as gland parenchyma, muscle, dermis, or adipose tissue.5,10Infiltrating tumor cells are typically surrounded by fibrous stroma and lymphocytes, and it is important to differentiate true infiltration from a multifocal growth pattern of benign cells.6,10 The differential diagnosis of BCAC includes other tumors that contain basaloid nests and hyalinized basement membranes, including adenoid cystic carcinoma (solid variant), basaloid squamous cell carcinoma, and infiltrating cutaneous basal cell carcinoma. Adenoid cystic carcinoma is differentiated by the presence of irregular nuclei, high mitotic rates, frequent central necrosis, and pseudocysts containing amorphous basophilic material; it also lacks the dual light-dark populations that are observed in BCAC.6,8,9Basaloid squamous cell carcinoma arises in regions uncommon to BCAC, and it is typically associated with conventional squamous cell carcinoma or dysplastic changes in the overlying epithelium.9Cutaneous basal cell carcinoma is usually excluded by clinical history, but the presence of myoepithelial differentiation or perineural invasion favors BCAC rather than basal cell carcinoma.4 BCAC typically presents as a slow-growing asymptomatic mass. Biopsy samples obtained via fine-needle aspiration are often indeterminate, requiring surgical excision and permanent section to achieve a final diagnosis. Because BCAC is a low-grade lesion, the tumor can be adequately managed using wide local excision. For parotid lesions, this involves a superficial or total parotidectomy with preservation of the facial nerve. Elective neck dissection is reserved for cases presenting with definitive lymphadenopathy. BCAC of the minor salivary glands is associated with a higher likelihood of vascular and perineural invasion, and several authors have recommended adjuvant radiotherapy for treatment of these lesions.6 Although the collective experience with BCAC is limited, available data suggest that it carries a moderate potential for recurrence and a low potential for metastasis or death. In a group of 46 cases with available outcome data (median follow-up, 36 months; range, 5-192 months), Muller and Barnes4identified 17 cases (37%) of local recurrence, 4 cases (8%) of cervical lymph node metastasis, and 2 cases (4%) of distant metastasis. Only 1 patient (2%) died of extensive tumor spread within the neck. This 37% recurrence rate underscores the importance of achieving complete resection and negative margins during surgery. In another series of 11 BCACs arising from minor salivary glands (median follow-up, 48 months; range, 12-172 months), Fonseca and Soares7identified 8 cases (73%) of local recurrence, 2 cases (18%) of cervical lymph node metastasis, and 4 deaths (36%). These data suggest that BCAC of minor salivary gland origin may behave more aggressively. Finally, long-term follow-up of BCAC is recommended regardless of location, because recurrent lesions have been identified as many as 19 years after initial presentation.5 Return to Quiz Case 1. References 1. Seifert GSobin LH Histological Typing of Salivary Gland Tumours. 2nd ed. New York, NY Springer-Verlag NY Inc1991; 2. Ellis GLAuclair PL Tumors of the Salivary Glands. Washington, DC Armed Forces Institute of Pathology1996; Atlas of Tumor Pathology 3rd ser (pt 17) Google Scholar 3. Nagao TSugano IIshida Y et al. Basal cell adenocarcinoma of the salivary glands: comparison with basal cell adenoma through assessment of cell proliferation, apoptosis, and expression of p53 and bcl-2. Cancer 1998;82 (3) 439- 447PubMedGoogle ScholarCrossref 4. Muller SBarnes L Basal cell adenocarcinoma of the salivary glands: report of seven cases and review of the literature. Cancer 1996;78 (12) 2471- 2477PubMedGoogle ScholarCrossref 5. Ellis GLWiscovitch JG Basal cell adenocarcinomas of the major salivary glands. Oral Surg Oral Med Oral Pathol 1990;69 (4) 461- 469PubMedGoogle ScholarCrossref 6. Jayakrishnan AElmalah IHussain KOdell EW Basal cell adenocarcinoma in minor salivary glands. Histopathology 2003;42 (6) 610- 614PubMedGoogle ScholarCrossref 7. Fonseca ISoares J Basal cell adenocarcinoma of minor salivary and seromucous glands of the head and neck region. Semin Diagn Pathol 1996;13 (2) 128- 137PubMedGoogle Scholar 8. Khalil MArthurs B Basal cell adenocarcinoma of the lacrimal gland. Ophthalmology 2000;107 (1) 164- 168PubMedGoogle ScholarCrossref 9. Parashar PBaron EPapadimitriou JCOrd RANikitakis NG Basal cell adenocarcinoma of the oral minor salivary glands: review of the literature and presentation of two cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103 (1) 77- 84PubMedGoogle ScholarCrossref 10. Hirsch DLMiles CDierks E Basal cell adenocarcinoma of the parotid gland: report of a case and review of the literature. J Oral Maxillofac Surg 2007;65 (11) 2385- 2388PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Otolaryngology - Head & Neck Surgery American Medical Association

Pathology Quiz Case 1: Diagnosis

Archives of Otolaryngology - Head & Neck Surgery , Volume 136 (1) – Jan 18, 2010
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References (10)

Publisher
American Medical Association
Copyright
Copyright © 2010 American Medical Association. All Rights Reserved.
ISSN
0886-4470
eISSN
1538-361X
DOI
10.1001/archoto.2009.180-b
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Abstract

Diagnosis: Basal cell adenocarcinoma (BCAC) BCAC is a rare salivary gland cancer that was largely undefined until the early 1990s, when it was first incorporated into the World Health Organization's Histological Typing of Salivary Gland Tumors.1Before acquiring a unique identity, BCAC had been reported under several names, including basaloid salivary carcinoma, carcinoma ex monomorphic adenoma, malignant basal cell adenoma, and malignant basal cell tumor.2BCAC is a low-grade malignant neoplasm and the malignant counterpart of basal cell adenoma. It presents at a mean age of 60 years and exhibits no sex predilection.2-4Incidence estimates range from 0.6% of major salivary gland tumors to 1.6% of all salivary neoplasms.2,3Most cases arise de novo, with only 23% representing malignant transformation of a basal cell adenoma.4,5Nine out of 10 BCACs involve the parotid gland, but rare examples have been identified in the submandibular gland, sublingual gland, buccal mucosa, lip, tongue, nasal cavity, sinuses, and lacrimal gland.4,6-8 The microscopic appearance of BCAC features 2 populations of basaloid cells: (1) small darkly staining cells with sparse cytoplasm and basophilic nuclei, and (2) large lightly staining polygonal cells with more prominent cytoplasm, pale nuclei, and central eccentric nucleoli. The basaloid cells exist in variable ratios and organize themselves into 4 patterns: solid, membranous, trabecular, and tubular. The solid variant is most common and exhibits tumor nests separated by intervening collagenous stroma, as in this case. In cases in which multiple architectural patterns exist within a single tumor, classification is based on the most predominant configuration.4,5Very limited data suggest that the solid variant is more likely to exhibit perineural growth, intravascular growth, and metastastatic dissemination, although the prognostic value of this histologic subtype remains to be shown.2,4 BCAC rarely exhibits cellular pleomorphism, but occasional mitotic figures and small areas of necrosis may be observed.4,5,8Vascular or perineural invasion occurs in 25% of cases.8The basaloid cells display both epithelial and myoepithelial phenotypes, and their immunohistochemical profiles show variable reactivity for cytokeratin, carcinoembryonic antigen, epithelial membrane antigen, S-100 protein, smooth-muscle actin, and vimentin.4,7Although the genetic properties of BCAC are still poorly defined, many of these tumors express p53, bcl-2, and epithelial growth factor receptor.3,9As many as 10% to 14% of individuals with BCAC develop synchronous cutaneous lesions such as eccrine cylindroma, trichoepithelioma, or eccrine spiradenoma; this “skin-salivary gland tumor diathesis” suggests a common genetic origin that remains to be investigated.4,5,10 BCAC and basal cell adenoma possess very similar cell populations, and these 2 entities are often indistinguishable based on cytologic features alone.1A diagnosis of BCAC requires invasion into adjacent structures such as gland parenchyma, muscle, dermis, or adipose tissue.5,10Infiltrating tumor cells are typically surrounded by fibrous stroma and lymphocytes, and it is important to differentiate true infiltration from a multifocal growth pattern of benign cells.6,10 The differential diagnosis of BCAC includes other tumors that contain basaloid nests and hyalinized basement membranes, including adenoid cystic carcinoma (solid variant), basaloid squamous cell carcinoma, and infiltrating cutaneous basal cell carcinoma. Adenoid cystic carcinoma is differentiated by the presence of irregular nuclei, high mitotic rates, frequent central necrosis, and pseudocysts containing amorphous basophilic material; it also lacks the dual light-dark populations that are observed in BCAC.6,8,9Basaloid squamous cell carcinoma arises in regions uncommon to BCAC, and it is typically associated with conventional squamous cell carcinoma or dysplastic changes in the overlying epithelium.9Cutaneous basal cell carcinoma is usually excluded by clinical history, but the presence of myoepithelial differentiation or perineural invasion favors BCAC rather than basal cell carcinoma.4 BCAC typically presents as a slow-growing asymptomatic mass. Biopsy samples obtained via fine-needle aspiration are often indeterminate, requiring surgical excision and permanent section to achieve a final diagnosis. Because BCAC is a low-grade lesion, the tumor can be adequately managed using wide local excision. For parotid lesions, this involves a superficial or total parotidectomy with preservation of the facial nerve. Elective neck dissection is reserved for cases presenting with definitive lymphadenopathy. BCAC of the minor salivary glands is associated with a higher likelihood of vascular and perineural invasion, and several authors have recommended adjuvant radiotherapy for treatment of these lesions.6 Although the collective experience with BCAC is limited, available data suggest that it carries a moderate potential for recurrence and a low potential for metastasis or death. In a group of 46 cases with available outcome data (median follow-up, 36 months; range, 5-192 months), Muller and Barnes4identified 17 cases (37%) of local recurrence, 4 cases (8%) of cervical lymph node metastasis, and 2 cases (4%) of distant metastasis. Only 1 patient (2%) died of extensive tumor spread within the neck. This 37% recurrence rate underscores the importance of achieving complete resection and negative margins during surgery. In another series of 11 BCACs arising from minor salivary glands (median follow-up, 48 months; range, 12-172 months), Fonseca and Soares7identified 8 cases (73%) of local recurrence, 2 cases (18%) of cervical lymph node metastasis, and 4 deaths (36%). These data suggest that BCAC of minor salivary gland origin may behave more aggressively. Finally, long-term follow-up of BCAC is recommended regardless of location, because recurrent lesions have been identified as many as 19 years after initial presentation.5 Return to Quiz Case 1. References 1. Seifert GSobin LH Histological Typing of Salivary Gland Tumours. 2nd ed. New York, NY Springer-Verlag NY Inc1991; 2. Ellis GLAuclair PL Tumors of the Salivary Glands. Washington, DC Armed Forces Institute of Pathology1996; Atlas of Tumor Pathology 3rd ser (pt 17) Google Scholar 3. Nagao TSugano IIshida Y et al. Basal cell adenocarcinoma of the salivary glands: comparison with basal cell adenoma through assessment of cell proliferation, apoptosis, and expression of p53 and bcl-2. Cancer 1998;82 (3) 439- 447PubMedGoogle ScholarCrossref 4. Muller SBarnes L Basal cell adenocarcinoma of the salivary glands: report of seven cases and review of the literature. Cancer 1996;78 (12) 2471- 2477PubMedGoogle ScholarCrossref 5. Ellis GLWiscovitch JG Basal cell adenocarcinomas of the major salivary glands. Oral Surg Oral Med Oral Pathol 1990;69 (4) 461- 469PubMedGoogle ScholarCrossref 6. Jayakrishnan AElmalah IHussain KOdell EW Basal cell adenocarcinoma in minor salivary glands. Histopathology 2003;42 (6) 610- 614PubMedGoogle ScholarCrossref 7. Fonseca ISoares J Basal cell adenocarcinoma of minor salivary and seromucous glands of the head and neck region. Semin Diagn Pathol 1996;13 (2) 128- 137PubMedGoogle Scholar 8. Khalil MArthurs B Basal cell adenocarcinoma of the lacrimal gland. Ophthalmology 2000;107 (1) 164- 168PubMedGoogle ScholarCrossref 9. Parashar PBaron EPapadimitriou JCOrd RANikitakis NG Basal cell adenocarcinoma of the oral minor salivary glands: review of the literature and presentation of two cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103 (1) 77- 84PubMedGoogle ScholarCrossref 10. Hirsch DLMiles CDierks E Basal cell adenocarcinoma of the parotid gland: report of a case and review of the literature. J Oral Maxillofac Surg 2007;65 (11) 2385- 2388PubMedGoogle ScholarCrossref

Journal

Archives of Otolaryngology - Head & Neck Surgery – American Medical Association

Published: Jan 18, 2010

Keywords: adenocarcinoma,neoplasms,basal cells,adenoma, basal cell,adenoid cystic carcinoma,necrosis

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