Mucoepidermoid Carcinoma with Spindle Cell Change: A Low-grade Lesion Potentially Mistaken for Sarcomatoid Dedifferentiation

Abstract

An unusual case of mucoepidermoid carcinoma (MEC) of intraoral minor salivary gland origin with spindled morphology was presented. A fascicular stream of bland spindle cells from typical MEC areas amounted to more than 70% of the tumor. Spindle population had features consistent with immunohistochemical and ultrastructural profiles of intermediate cells and lacked overexpression of p53 and cyclin D1. There was no difference in the Ki-67 index between two distinct components. Awareness of extensive spindle cell change replacing a significant portion of low-grade MEC is crucial to avoid an erroneous interpretation of dedifferentiated sarcomatoid transformation.

Spindle Cell Mucoepidermoid Carcinoma of the Palatine Tonsil With CRTC1-MAML2 Fusion Transcript: Report of a Rare Case in a 17-Year-Old Boy and a Review of the Literature

“…8,9 MEC with a focal spindle cell component is not uncommonly observed, but MEC with a predominance of spindle cells is rare and has only been documented in a few previous studies. [1][2][3][4] In 1964, Lucas and colleagues published a seminal article describing extensive areas of spindle cell change in MEC, 3 and in 1986, a spindle cell variant with high nuclear grade was described by Love et al 4 It took more than 2 decades until 2 cases of MEC with a predominance of spindle cell morphology reemerged in the literature in English, this time with lowgrade morphology. 1,2 The tumor described by Ide et al 1 in 2008 showed solid and cystic architecture where the former component contained streaming fascicles of neoplastic cells with spindle cell morphology featuring low nuclear grade amounting to more than 70% of the tumor volume.…”

“…The spindle cell variant of MEC (spMEC), as the name implies, is predominantly composed of spindle cells and is a rare tumor, with only a few documented cases in the literature. [1][2][3][4] These spMECs were located at the posterior maxillary region, oral cavity, including the floor of the mouth as well as in the submandibular gland. [1][2][3][4] A high proportion of MEC of salivary glands as well as of other organs is known to harbor a t (11;19) translocation, which results in fusion of the MEC translocated 1 (MECT1, also CRTC1) gene on chromosome 19p13 with the mastermind-like 2 (MAML2) gene on chromosome 11q21.…”

“…[1][2][3][4] These spMECs were located at the posterior maxillary region, oral cavity, including the floor of the mouth as well as in the submandibular gland. [1][2][3][4] A high proportion of MEC of salivary glands as well as of other organs is known to harbor a t (11;19) translocation, which results in fusion of the MEC translocated 1 (MECT1, also CRTC1) gene on chromosome 19p13 with the mastermind-like 2 (MAML2) gene on chromosome 11q21. 5 This translocation is found in both conventional as well as unusual types of MECs, including clear cell predominant, oncocytic, and Warthin-like variants.…”

Diagnostic Accuracy and Pitfalls in Fine Needle Aspiration Cytology Of Salivary Gland Lesions.

“…On review of the smears only spindle cell component was seen which led to an erroneous diagnosis of myoepithelioma. Neoplastic myoepithelium in salivary gland tumors, is prone to assume a spindle cell configuration and has been reported to undergo dedifferentiation [7] .…”

Sclerosing mucoepidermoid carcinoma: specific histologic variant or nonspecific morphologic pattern?

“…More than eight potential variants have been tabulated in a recent review article (1), including unicystic (5), sclerosing (2), oncocytic (2,4), clear cell (6,7), spindle cell (8), goblet cell aggressive (3), psammomatous (9,10) and sebaceous types (11). Among them, the sclerosing variant epitomizes the stromal fibrosis and hyalinization accompanied by a dense infiltrate of lymphoplasmacytic cells with or without eosinophilia (1)(2)(3)(4).…”