Mesenchymal Neoplasms of Salivary Glands: A Clinicopathologic Study of 68 Cases

Salivary gland neoplasms are uncommon, and most exhibit epithelial differentiation. Mesenchymal neoplasms of the salivary gland are rare, and the incidence ranges from 1.9% to 5%. The aim of this study is to identify the types and clinical-pathological features of mesenchymal salivary neoplasm and review their differential diagnosis. A retrospective search for mesenchymal neoplasms of salivary glands from our institution's pathology archives from the 2004–2021 period and consultation files of one of the authors (AER) was performed. The clinical data were obtained from available medical records, and the histological slides and ancillary studies were retrieved and reviewed. We identified a total of 68 cases that form the study cohort. Thirty-five patients were male, and thirty-three patients were female, with a mean age of 48 years (range, 7 months–79 years), and the male to female ratio was 1:.94. Sixty-three (92.6%) of sixty-eight tumors were benign and included: 38 (56%) lipomas, 9 (13%) hemangiomas, 7 (10.3%) schwannomas, 3 (4.4%) neurofibromas, 3 (4.4%) lymphangioma, 2 (3%) solitary fibrous tumors, 1 (1.5%) myofibroma. Five of sixty-eight (7.4%) were malignant and included: 3 (4.4%) Adamantinoma-like Ewing sarcomas, 1 (1.5%) malignant peripheral nerve sheath tumor (MPNST), and 1 (1.5%) malignant solitary fibrous tumor. The involved sites included: parotid (55), submandibular gland (5), parapharyngeal space (5), buccal mucosa minor salivary gland (2), and sublingual gland (1). Sixty-seven patients underwent surgical resection. One patient with lymphangioma manifested a recurrence/persistence a week post-surgery. One patient with a parotid hemangioma developed post-operative numbness, and another patient developed chronic postauricular pain after surgery. Two patients with MPNST and one patient with adamantinoma-like Ewing sarcoma underwent neoadjuvant chemoradiation and were disease-free after treatment. The remaining 37 patients with available follow-up ranging from 7 days to 96 months (mean, 18 months) had a favorable outcome and were disease-free after treatment. Mesenchymal neoplasms of salivary gland are rare; most are benign and demonstrate adipocytic, endothelial, and schwannian differentiation; awareness of their development is important for adequate diagnosis. The mainstay of treatment is surgical excision, with the extent determined by tumor type. Adjuvant therapy is reserved for high-grade sarcomas and may be given in a neoadjuvant or adjuvant setting.