Sclerosing mucoepidermoid carcinoma of minor salivary glands: a case report

Sclerosing mucoepidermoid carcinoma of the salivary glands: report of three cases with special concern to the counterpart accompanied by eosinophilia

Sclerosing mucoepidermoid carcinoma (SMC) is described as a "sclerosing variant" of mucoepidermoid carcinoma, and it is characterized by dense fibrosis and sclerosis of the stroma. SMC with eosinophilia (SMCE) is another and more rare subtype characterized by eosinophilia in addition to the sclerotic stroma common to SMC. However, unlike SMC, SMCE is not listed in the current 4th edition of WHO classification. Here, we describe three cases: one SMC in the parotid gland, one SMCE in the submandibular gland and one SMCE in the minor salivary gland of the oral cavity. The patients included a 71-year-old Japanese male, a 74-year-old Japanese female, and an 81-year-old Japanese female. They each complained of mass formation and underwent surgical resection. Histologically, the tumors mainly consisted of squamous cells with scarce keratinization that formed irregular large and small nests along with cystic structures containing mucous cells against the background of sclerotic stroma. One oral SMCE showed fine nesting and trabecular invasion. The two SMCEs included dense aggregates of eosinophils as well as more prominent lymphoid infiltration. Fluorescence in situ hybridization for MAML2 confirmed split signals in SMC, but not in SMCE.

Sclerosing variant of mucoepidermoid carcinoma: a diagnostic challenge

The sclerosing variant of mucoepidermoid salivary gland carcinoma is extremely rare. It is nearly impossible to diagnose this condition preoperatively. We present a case of a 23-year-old woman with a 1-year history of left parotid enlargement with inconclusive fine-needle aspiration cytology results. MRI showed an irregular parotid mass, and subsequent partial parotidectomy confirmed the diagnosis. We discuss the diagnostic pitfalls of this condition and provide a review of the literature surrounding its pathogenesis and management.

Sclerosing Mucoepidermoid Carcinoma of the Submandibular Gland Presenting as Chronic Sialadenitis: A Case Report and Review of Literature

Sclerosing mucoepidermoid carcinoma of the salivary gland (SMEC) is a rare subtype of mucoepidermoid carcinoma (MEC), first described in 1987 by Chan and Saw. As far as we are aware, only 30 cases have been published since then. Most cases were located in the parotid gland with some cases described in the submandibular and minor salivary glands. SMEC typically presents as a long-standing mass, with a non-specific enhancing appearance on imaging and is often non-diagnostic on fine needle aspiration, making pre-operative diagnosis very difficult. It is characterised by dense sclerosis within an otherwise typical MEC, frequently with lymphoid proliferation and eosinophils at the periphery. The histological diagnosis of SMEC can be challenging, as the sclerosis may obscure the other morphological features, which can lead to misdiagnosis. Grading can also be difficult, and the prognostic value of grading for SMEC remains unclear. Herein is described a new case of SMEC, presenting clinically as chronic sialadenitis in the left submandibular gland of a 41 year old male. A brief literature review and the issues surrounding diagnosis and grading are also discussed.

Sclerosing mucoepidermoid carcinoma of the sublingual gland

INTRODUCTION

Sclerosing mucoepidermoid carcinoma of the salivary gland is a rare subtype of mucoepidermoid carcinoma. The most common site of sclerosing mucoepidermoid carcinoma of the salivary glands is the parotid gland, followed by the submandibular gland, and the minor salivary glands.

OBSERVATION

Here we report the first case of sclerosing mucoepidermoid carcinoma of the sublingual gland.

DISCUSSION

Clinicians should consider sclerosing mucoepidermoid carcinoma in the differential diagnosis of salivary gland neoplasm. Surgical excision with clear margins seems to be a sufficient initial treatment option for sclerosing mucoepidermoid carcinoma of the salivary gland.

Local recurrence of sclerosing mucoepidermoid carcinoma with eosinophilia in the upper lip: a case report

INTRODUCTION

Sclerosing mucoepidermoid carcinoma with eosinophilia is a rare morphological variant of thyroid carcinoma associated with Hashimoto's disease. To date, only three such tumors have been reported in the minor salivary glands. We describe the first case, to the best of our knowledge, of recurrent sclerosing mucoepidermoid carcinoma with eosinophilia in the minor salivary glands of the upper lip.

CASE PRESENTATION

A 61-year-old Japanese man was referred to our hospital with a mass in his median upper lip of four years' duration. An examination of his median upper lip revealed a well-defined tumor measuring 9 × 12 mm in diameter, which was subsequently resected. Three years after the first surgery, the tumor recurred and was resected. Both tumors were confirmed by histopathology to be sclerosing mucoepidermoid carcinoma with eosinophilia. Neither recurrence nor metastasis was observed in three and a half years of follow-up after the second surgery.

CONCLUSION

Our findings indicate that sclerosing mucoepidermoid carcinoma with eosinophilia can originate in the minor salivary glands and may be clinically or pathologically misdiagnosed as other conditions.

'Palatal swelling in a patient suffering from filariasis'

Sclerosing mucoepidermoid carcinoma (SMEC) is a distinct but an uncommon salivary gland neoplasm with only 19 cases reported in English literature till date. Densely collagenous sclerotic stroma, resemblance to other benign lesions and rarity of this tumour often makes the diagnosis of SMEC challenging. Here we report a case of SMEC in a 73-year old female patient suffering from filariasis. Clinical, radiological, fine needle aspiration biopsy, gross and histopathological features are discussed with detailed review of literature and probable pathogenesis.

IgG4(+) plasma cells in sclerosing variant of mucoepidermoid carcinoma

IgG4-related sclerosing disease is a recently described syndrome with unique histologic features characterized by intense lymphoplasmacytic infiltrates with increased IgG4 plasma cells and dense stromal sclerosis. The disease spectrum frequently includes benign inflammatory diseases, such as autoimmune pancreatitis, cholangitis, and chronic sclerosing sialadenitis (CSS). Mucoepidermoid carcinoma (MEC) is the most common primary malignancy in the salivary gland. The rare sclerosing variant of MEC is characterized by dense stromal sclerosis and lymphoplasmacytic infiltrates. Our goal was to further characterize lymphoplasmacytic infiltrates with respect to IgG4 expression. Six sclerosing MECs from our pathology service over the past 20 years were selected. In addition, 11 regular MECs with lymphoplasmacytic infiltrates, 4 CSS cases, and 12 nonsclerosing chronic sialadenitis cases were evaluated. None of the sclerosing MEC patients had IgG4-related sclerosing disease. The absolute number of IgG4 plasma cells was significantly increased in sclerosing MEC as compared with the regular type (75 vs. 20 per image field; P<0.05). Furthermore, the proportion of IgG4/IgG plasma cells was markedly elevated in sclerosing MEC as compared with the regular type (46.5% vs. 17%; P<0.05). In CSS, IgG4/IgG ratio was significantly increased as compared with nonsclerosing chronic sialadenitis (54% vs. 6.73%; P<0.01). This study is the first to demonstrate increased IgG4 plasma cells in sclerosing MEC. The association of elevated IgG4 plasma cells with increased fibrosis in the sclerosing variant of MEC suggests a role of IgG4 plasma cells in fibrogenesis and may be a new concept related to sclerosis in cancer.

Sclerosing mucoepidermoid carcinoma of the salivary glands

Mucoepidermoid carcinoma (MEC) comprises approximately 30% of all salivary gland malignancies, making it the most common malignant tumor of the salivary glands. Multiple histologic variants with a wide range of differentiation have been described. Sclerosing MEC (SMEC) is a rare subtype that may be misdiagnosed as a benign reactive condition or low-grade non-SMEC malignancy. We report 4 cases of SMEC and evaluated them with Her-2/neu and MIB-1 to determine whether an association exists between the histologic grade and immunohistochemical findings. In 3 cases, histologic examination demonstrated relatively well-circumscribed, nonencapsulated tumors composed of extensive central sclerosis with keloid-like stroma and scattered epithelial islands of low-grade MEC. In the fourth case, the tumor showed similar sclerotic stroma; but the epithelial component was of intermediate grade. In all 4 cases, eosinophils and neutrophils were part of the inflammatory infiltrate; and the edges were surrounded by lymphoid tissue, with germinal center formation and residual epithelial islands. A Mayer mucicarmine stain revealed abundant intracytoplasmic mucin. We found MIB-1 labeling indices of 5% or less in cases 1, 2, and 3 and 12% in case 4, suggesting an association between MIB-1 index and tumor grade. The tumors were negative for Her-2/neu in all 4 cases. The latter seems to bear no relationship to tumor grade.

Sclerosing mucoepidermoid carcinoma of the parotid gland

Mucoepidermoid carcinoma is the most common malignant tumor of the parotid gland. Its clinical behavior is determined by the relative ratio of mucous and epidermoid cells with pathologic high-grade tumors containing a greater proportion of epidermoid cells. Sclerosing mucoepidermoid carcinoma is a rarely reported variant with unclear long-term clinical behavior. A 23-year-old female was found to have a deep lobe parotid mass on imaging studies. Preoperative evaluation was non-diagnostic. Intraoperatively, the tumor was found to be adherent to the lower division of the facial nerve and portions of the posterior digastric muscle. Frozen section specimens showed only squamous metaplasia with background inflammatory fibrosis. Final pathological analysis demonstrated multiple solid and cystic nests and glands within a background of dense, sclerotic, collagenized stroma and inflammatory infiltrate consistent with low-grade sclerosing mucoepidermoid carcinoma. Sclerosing mucoepidermoid carcinoma is a very rare salivary gland tumor with uncertain behavior. Complete surgical excision with tumor-free margins with preservation of the facial nerve (in the absence of clinical invasion) is recommended. Postoperative radiation therapy is suggested for positive or close margins given the adherent nature of the tumor and the risk of recurrence and distant disease found in some case reports. Patients should be followed closely with serial MRI imaging studies of the tumor bed with complete clinical evaluation of the regional lymphatics and chest to evaluate for evidence of recurrence or metastasis.

Sclerosing mucoepidermoid carcinoma of the oral cavity

Sclerosing mucoepidermoid carcinoma (SMEC) with eosinophilia is a rare but distinctive tumor usually affecting the thyroid. SMEC involvement of salivary gland is exceptional, with only six cases in the literature. We present here the first case of an intermediate-grade SMEC, arising from the intraoral minor salivary glands. A particularly interesting finding is the cytoplasmic accumulation of eosinophilic hyaline granules in carcinoma cells, similar to aberrant zymogen-like granules previously described in salivary sclerosing polycystic adenosis.

Sclerosing Mucoepidermoid Carcinoma of the Parotid Gland

Although mucoepidermoid carcinoma is the most common primary malignancy of the salivary glands, the sclerosing morphologic variant of this tumor is extremely rare, with only 6 reported cases. As its name suggests, sclerosing mucoepidermoid carcinoma is characterized by an intense central sclerosis that occupies the entirety of an otherwise typical tumor, frequently with an inflammatory infiltrate of plasma cells, eosinophils, and/or lymphocytes at its peripheral regions. The sclerosis associated with these tumors may obscure their typical morphologic features and result in diagnostic difficulties. Tumor infarction and extravasation of mucin eventuating in reactive fibrosis are 2 mechanisms of formation that have been suggested as underlying this morphologic variant. We describe herein another case of sclerosing mucoepidermoid carcinoma that was diagnosed in a 44-year-old woman and review the relevant literature. Morphologic evidence in support of the mucin extravasation hypothesis was identified, as small pools of mucin were present throughout the tumor. However, there was no concentration of the mucin pools near the areas with the most viable tumor cells, which would have provided evidence for a temporal sequence that eventuates in lack of mucin in the most sclerotic regions.