Anatomic Pathology / FNA OF LYMPHOID LESIONS OF THE SALIVARY GLANDS

Fine-Needle Aspiration Cytology of Lymphoproliferative Lesions Involving the Major Salivary Glands David C. Chhieng, MD,1 Joan F. Cangiarella, MD,2 and Jean-Marc Cohen, MD3 Key Words: Needle biopsy; Cytology; Salivary gland; Lymphoma; Lymphoid hyperplasia

Fine-needle aspiration biopsy (FNA) is an accurate and cost-effective procedure for evaluating salivary gland lesions. Lymphoproliferative lesions may manifest as salivary gland enlargement. We report our experience with 43 cases of reactive and neoplastic lymphoproliferative lesions of the salivary glands evaluated by FNA, including 23 cases of reactive lymphoid hyperplasia and 20 neoplastic lymphoproliferative processes. The latter included 2 multiple myelomas and 18 non-Hodgkin lymphomas (small lymphocytic lymphoma/chronic lymphocytic leukemia, 1; small cleaved cell lymphoma, 1; lymphoplasmacytoid lymphoma, 1; mucosa-associated lymphoid tissue lymphoma, 2; mixed cell lymphoma, 4; lymphoblastic lymphoma, 1; and large cell lymphoma, 8). There were no false-negative diagnoses. Aspiration smears from 3 patients with reactive lymphoid hyperplasia and 4 patients with malignant lymphoma initially were interpreted as atypical lymphoid proliferations or as suggestive of malignant lymphoma. Thus, FNA had a sensitivity of 100% and a specificity of 87%. The majority of patients were treated medically without surgical intervention. Among the patients who underwent surgical resection of the salivary gland, 7 had an equivocal cytologic diagnosis and 2 had a benign cytologic diagnosis, but their parotid swelling failed to regress despite medical treatment. In most instances, FNA provides useful information for subsequent disease management and obviates surgical intervention.

© American Society of Clinical Pathologists

Fine-needle aspiration biopsy (FNA) is well accepted as a reliable, minimally invasive, and cost-effective procedure for evaluating salivary gland lesions.1-5 FNA offers information that helps in disease management and, in some instances, obviates unnecessary surgery.3 The majority of salivary gland lesions encountered are epithelial, and their cytologic features have been well described in the literature. Because of the intimate relationship of the lymphoid tissue and the glandular parenchyma of the salivary gland, both reactive and neoplastic lymphoproliferative processes may arise de novo or secondarily involve the intraglandular lymphoid tissue, the glandular parenchyma, or both. Since the clinical and therapeutic implications of these lesions differ considerably, it is important to distinguish a lymphoid lesion from a nonlymphoid lesion and to differentiate a reactive lymphoid process from a neoplastic process. Few reports have demonstrated the value of FNA for diagnosing lymphoproliferative lesions of the salivary glands.6-10 In this article, we describe our experience with 43 cases of reactive and neoplastic lymphoproliferative lesions of the salivary glands diagnosed by FNA. The cytologic features are described with a discussion of the differential diagnoses. The accuracy of FNA for establishing these diagnosis also was determined.

Materials and Methods Forty-three lymphoid lesions of the salivary glands (4.9%) evaluated by FNA were identified in a series of 873 salivary gland FNAs from the files of the pathology department of New York University Medical Center/Bellevue Hospital Medical Center, New York, NY, during an 8-year period (1991 to 1998). Warthin tumors, chronic sialadenitis, Am J Clin Pathol 2000;113:563-571

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Abstract

Chhieng et al / FNA OF LYMPHOID LESIONS OF THE SALIVARY GLANDS

Results The 43 aspiration biopsy specimens were from 43 patients (18 females and 25 males) with an age range of 1 to 89 years (mean, 55 years). The clinical findings are given in ❚Table 1❚. Forty patients had a unilateral parotid mass, 2 a unilateral submandibular mass, and 1 bilateral parotid enlargement. A known history of malignant lymphoma was available at the time of FNA for 14 patients. Three patients were seropositive for HIV. Twenty-three aspiration smears showed reactive lymphoid hyperplasia and 20 neoplastic lymphoproliferative processes. The latter included 2 multiple myelomas and 18 non-Hodgkin lymphomas (small lymphocytic lymphoma/chronic lymphocytic leukemia, 1; small cleaved cell lymphoma, 1; lymphoplasmacytoid lymphoma, 1; mucosa-associated lymphoid tissue lymphoma [MALT], 2; mixed cell lymphoma, 4; lymphoblastic lymphoma, 1; and large cell lymphoma, 8). The aspiration smears from the 23 patients with reactive lymphoid hyperplasia were cellular. Sixteen cases were characterized by a heterogeneous population of small and large lymphocytes in various stages of maturation. In addition, occasional immunoblasts, mature plasma cells, tingible body macrophages, and lymphohistiocytic aggregates also were present. Rare benign acinar epithelium was noted in 8 cases. A diagnosis of reactive lymphoid hyperplasia was made based on cytology alone in these 16 cases. In 2 of the remaining 7 cases, there was a predominant population of small lymphocytes. In another 5 cases, the aspiration smears contained a mixed population of small and large lymphocytes without readily identifiable tingible body macrophages. 564

Am J Clin Pathol 2000;113:563-571

The aspiration smears of 3 of these 5 cases also contained scattered large atypical cells with prominent nucleoli ❚Image 1❚. These findings raised the question of Hodgkin lymphoma and were interpreted as atypical lymphoproliferative lesions. Flow cytometry, performed in these 7 cases, revealed a polyclonal B-cell population. The 3 patients with atypical findings on FNA underwent surgical resection; histologic examination revealed florid follicular lymphoid hyperplasia involving intraglandular lymph nodes in 2 cases and progressive transformation of the germinal centers in 1 case. Two additional patients underwent surgical resection because of persistent parotid swellings despite antibiotic therapy; histologic examination confirmed the cytologic diagnosis of reactive follicular lymphoid hyperplasia. The remaining patients were treated conservatively, and the salivary gland swellings regressed clinically. The aspiration smears from the 2 cases of multiple myeloma were cellular and consisted of mature and immature plasma cells ❚Image 2❚. The mature plasma cells had the typical cartwheel chromatin pattern, paranuclear clearing, and a moderate amount of basophilic cytoplasm. Immature and atypical plasma cells had less clumped chromatin and prominent nucleoli. Binucleation and mitotic figures also were noted. Flow cytometry performed on aspirated material from 1 case revealed monotypic staining with kappa light chain. The aspiration smears from the small lymphocytic lymphoma consisted of a uniform population of small lymphocytes with scant cytoplasm, round nuclei, and clumped chromatin ❚Image 3❚. Occasional larger lymphocytes with a moderate amount of pale cytoplasm and prominent nucleoli consistent with prolymphocytes also were noted. An admixture of small round lymphocytes and plasmacytoid lymphocytes characterized the aspiration smears of the lymphoplasmacytic lymphoma ❚Image 4❚. The plasmacytoid lymphocytes had abundant basophilic cytoplasm, eccentric nuclei, and rare intranuclear cytoplasmic inclusions (Dutcher bodies). The cytologic findings of small cleaved cell lymphoma included a monotonous population of small to medium-sized lymphocytes with irregular or convoluted nuclei. Occasional (