Pleomorphic Adenoma With Extensive Lipometaplasia

Abstract

We report a series of three cases of pleomorphic adenoma with extensive lipometaplasia, a recently described subtype of pleomorphic adenoma of salivary gland origin. Two patients were female and one male, ranging in age from 30 to 45 years. Two occurred in the minor salivary glands of the lip and palate, respectively, and one in the parotid. Typical histologic findings are presented. In addition, one case consists of a proliferation of spindle cells with an interesting combination of mature adipose tissue, hyaline cartilage, and bone in the absence of ductal structures. The differential diagnosis, as it pertains to other fat-containing tumors (such as lipoadenoma, spindle cell lipoma, interstitial lipomatosis, and benign mesenchymoma), is discussed. It is likely that the ability of myoepithelial cells to undergo various metaplasias is the cause of the unusual histologic appearances of this tumor.

Fat-Containing Salivary Gland Tumors: A Review

“…Immunohistochemical examination confirms the epithelial (ductal and basal) or myoepithelial line of differentiation in these tumors. Prominent areas of hyaline cartilage and trabecular bone were seen in one case [8]. The fatty component and the occasional heterologous differentiation in these lesions probably represent the well known capacity of neoplastic myoepithelium to show pluriform mesenchymal transdifferentiation [11].…”

“…Although scattered, isolated adipocytes might be encountered in classical pleomorphic adenomas more commonly if thoroughly searched for, pleomorphic adenomas and myoepitheliomas with extensive lipometaplasia comprising C20 % of the tumor is exceedingly uncommon with less than 15 reported cases in the English literature to date (10 pleomorphic adenomas and 5 myoepitheliomas) [3][4][5][6][7][8][9][10]. Approximately 80 % of tumors involved major salivary glands (11/12 in the parotid) with only three cases in minor glands.…”

Spindle cell lipoma of peri-parotid soft tissues. Report of a case and histogenetic considerations

“…In our case, the lipomatous tumor, with the typical morphological and immunohistochemical features of SCL, was well separated from the surrounding normal parotid parenchyma by a thick fibrous capsule, and it was considered as primarily arising from the peri-parotid gland soft tissues. Accordingly, both lipomatous pleomorphic adenoma or lipoadenoma were easily ruled out on the basis of the tumor site and absence of any epithelial/myoepithelial intra-tumoral component [14,15]. Among lipomatous tumors, a differential diagnosis was made with conventional lipoma, lipoma-like well-differentiated liposarcoma, and spindle cell liposarcoma.…”

Solitary Fibrous Tumor with Entrapment of Minor Salivary Gland Tissue: An Unusual Presentation That Requires Exclusion of Pleomorphic Adenoma

“…The classic microscopic features of PA consist of an epithelial proliferation with a myxoid background and many times, focal chondroid metaplasia. However, PA tends to show a morphological diversity that may simulate other benign and malignant tumors [17][18][19] (Table 3). For example, the epithelial component may show ductal formation and cribriform patterns that resemble adenoid cystic carcinoma.…”