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Intraoperative Consultation in Salivary Glands and Biopsy Diagnosis of Salivary Gland Neoplasms


Intraoperative Consultation in Salivary Glands

General Considerations ( Figs. 21-1 through 21-12 )

  • Intraoperative consultation (i.e., frozen section) in salivary gland pathology presents unique diagnostic challenges.

  • Majority of salivary gland neoplasms (approximately 80%) originate in parotid and submandibular glands:

    • Approximately 20% to 25% of neoplasms occurring in major salivary glands are malignant.

    • In parotid gland, most neoplasms arise in superficial lobe

  • Majority of minor salivary gland neoplasms originate in the oral cavity:

    • 50% to 60% or greater of minor salivary gland tumors are malignant.

  • Although any type of salivary gland neoplasm may occur in major and minor salivary glands, a number of salivary gland neoplasms predilect to major glands or to minor glands, including:

    • Predilection to major glands:

      • –

        Warthin tumor (parotid gland)

      • –

        Basal cell adenoma (parotid gland)

      • –

        Oncocytoma (parotid gland)

      • –

        Acinic cell carcinoma (parotid gland)

      • –

        Mammary analogue secretory carcinoma (parotid gland)

      • –

        Basal cell adenocarcinoma (parotid gland)

      • –

        Epithelial-myoepithelial carcinoma (parotid gland)

      • –

        Carcinoma ex pleomorphic adenoma (parotid gland)

        • ▪

          Salivary duct carcinoma (parotid gland)

        • ▪

          Oncocytic carcinoma (parotid gland)

        • ▪

          Others

    • Predilection to minor glands:

      • –

        Canalicular adenoma (lip)

      • –

        Cystadenoma (oral cavity)

      • –

        Polymorphous low-grade adenocarcinoma (palate)

      • –

        Clear cell carcinomas (oral)

      • –

        Cribriform adenocarcinoma of minor salivary glands (base of tongue, oral)

  • Major and minor salivary gland neoplasms share similar morphologic features but contrast in other ways that must be considered in their frozen section evaluation:

    • Majority of major salivary gland neoplasms are encapsulated, in part or completely:

      • –

        Major salivary gland benign neoplasms are circumscribed to encapsulated, lacking invasive growth and cytomorphologic features of malignancy:

        • ▪

          Some benign neoplasms may be multinodular with nodules separate from one another (e.g., pleomorphic adenoma, basal cell adenoma, canalicular adenoma, Warthin tumor).

        • ▪

          Some benign neoplasms may include foci within soft tissues, in particular recurrent pleomorphic adenomas.

      • –

        Major salivary gland malignant neoplasms show cytomorphologic features of malignancy and/or invasive growth:

        • ▪

          Cytomorphologically bland-appearing neoplasms may be malignant on the basis of infiltrative growth:

          • □

            Examples include adenoid cystic carcinoma, basal cell adenocarcinoma, epithelial-myoepithelial carcinoma, others.

        • ▪

          Noninvasive neoplasms may be malignant on the basis of identifying specific cell types or the presence of anaplastic cellular features:

          • □

            Examples of neoplasms with specific cell types diagnostic for malignancy include mucoepidermoid carcinoma, acinic cell carcinoma, others.

          • □

            Examples of neoplasms with anaplastic cellular features diagnostic for malignancy include all salivary gland neoplasms composed of histologically high-grade cytomorphology, including salivary duct carcinoma, high-grade carcinoma ex pleomorphic adenoma, high-grade adenocarcinoma, not otherwise specified and high-grade transformation (“dedifferentiation”) of lower grade salivary gland neoplasms.

      • –

        All minor salivary gland neoplasms are unencapsulated:

        • ▪

          Benign minor salivary gland neoplasms are circumscribed without invasive growth.

        • ▪

          Benign minor salivary gland neoplasms may be multinodular with nodules separate from one another (e.g., pleomorphic adenoma, basal cell adenoma, canalicular adenoma).

        • ▪

          Some benign neoplasms may include foci within soft tissues, in particular recurrent pleomorphic adenomas.

      • –

        Minor salivary gland malignant neoplasms show cytomorphologic features of malignancy and/or invasive growth.

        • ▪

          Cytomorphologically bland-appearing neoplasms may be malignant on the basis of infiltrative growth:

          • □

            Examples include adenoid cystic carcinoma, polymorphous low-grade adenocarcinoma, clear cell carcinomas, others.

        • ▪

          Noninvasive neoplasms may be malignant on the basis of identifying specific cell types or the presence of anaplastic cellular features:

          • □

            Examples of neoplasms with specific cell types diagnostic for malignancy include mucoepidermoid carcinoma, others.

          • □

            Examples of neoplasms with anaplastic cellular features diagnostic for malignancy include all salivary gland neoplasms composed of histologically high-grade cytomorphology, including salivary duct carcinoma; high-grade carcinoma ex pleomorphic adenoma; high-grade adenocarcinoma, not otherwise specified and high-grade transformation (“dedifferen­tiation”) of lower grade salivary gland neoplasms.

Fig. 21-1, Configuration of benign and malignant salivary gland neoplasms.

Fig. 21-2, Appropriate sectioning of salivary gland neoplasms.

Fig. 21-3, Chronic sialadenitis.

Fig. 21-4, Pleomorphic adenoma.

Fig. 21-5, Cellular pleomorphic adenoma.

Fig. 21-6, Myoepithelial-predominant PA.

Fig. 21-7, Recurrent pleomorphic adenoma.

Fig. 21-8, Intraoperative consultation, Warthin tumor, parotid gland.

Fig. 21-9, Mucoepidermoid carcinoma, low-grade.

Fig. 21-10, Adenoid cystic carcinoma.

Fig. 21-11, Acinic cell adenocarcinoma.

Fig. 21-12, Polymorphous low-grade adenocarcinoma.

Indications for Intraoperative Consultation in Salivary Gland Neoplasms

Major Glands

  • Indications for intraoperative consultation in major salivary gland neoplasms include:

    • To render a diagnosis (determine tumor type), which may include:

      • –

        Cases in which there has been an equivocal or inconclusive diagnosis by fine-needle aspiration biopsy (FNAB) or core biopsy

      • –

        Cases in which a prior diagnostic procedure (e.g., FNAB, biopsy) has not been attempted

    • To evaluate surgical margins of resection for adequacy of resection:

      • –

        May include measuring distance between tumor and surgical margin(s)

    • To determine if lymph node metastases are present:

      • –

        Identification of nodal metastasis may result in more extensive neck dissection.

      • –

        High-grade malignant salivary gland neoplasms have increased incidence of nodal metastasis at presentation, including:

        • ▪

          High-grade mucoepidermoid carcinoma, salivary duct carcinoma, others

    • To obtain tissue for ancillary studies; examples may include:

      • –

        Lymphoma evaluation

      • –

        Cytogenetic evaluation

      • –

        Less commonly, ultrastructural evaluation

Minor Glands

  • Indications for intraoperative consultation in minor salivary gland tumors include:

    • To render a diagnosis (determine tumor type), which may include:

      • –

        Cases in which there has been an equivocal or inconclusive diagnosis by fine-needle aspiration biopsy (FNAB) or core biopsy

      • –

        Cases in which a prior diagnostic pro­cedure (e.g., FNAB, biopsy) has not been attempted

    • To evaluate surgical margins of resection

    • To try to determine the presence of perineural invasion:

      • –

        Involvement of palatine nerves from pterygopalatine fossa is generally determined pre-operatively by radiographic imaging studies.

    • To determine osseous involvement that may necessitate resection of bone (palatine bone or maxilla)

    • Usually lymph node dissection is not performed for intraoral minor salivary gland neoplasms unless there is preoperative diagnosis of a high-grade malignancy.

    • If lymph nodes are excised, then a frozen section may be requested to exclude the presence of metastatic disease.

      • –

        Identification of nodal metastasis may result in more extensive neck dissection.

    • To obtain tissue for ancillary studies; examples may include:

      • –

        Lymphoma evaluation

      • –

        Cytogenetic evaluation

      • –

        Less commonly, ultrastructural evaluation

Surgeon's Expectations of the Intraoperative Assessment of Salivary Gland Neoplasms

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