C-kit expression in the salivary gland neoplasms adenoid cystic carcinoma, polymorphous low-grade adenocarcinoma, and monomorphic adenoma

Objective. Differentiating between adenoid cystic carcinomas (ACCs), polymorphous low-grade adenocarcinomas (PLGAs), and the monomorphic adenomas (including canalicular adenomas, trabecular adenomas, and basal cell adenomas) can present a diagnostic challenge, especially when examining tissue obtained from small incisional or fragmented biopsies. Recent studies have revealed that overexpression of the tyrosine kinase receptor protein c-kit occurs in a narrow subset of malignant neoplasms, including gastrointestinal stromal tumors, myeloid leukemias, seminomas, and ACCs. C-kit reportedly is not expressed in PLGAs. We compared the expression of the c-kit antigen in the malignant salivary gland neoplasms ACC and PLGA with its expression in salivary gland monomorphic adenoma (including canalicular adenoma and basal cell adenoma). Study design. Formalin-fixed paraffin-embedded sections of 49 salivary gland neoplasms (17 monomorphic adenomas, 17 PLGAs, and 15 ACCs) accessioned between 1989 and 2002 were retrieved from the files of the Department of Pathology, Long Island Jewish Medical Center, and were stained with an anti-c-kit polyclonal antibody. Results. C-kit reactivity was uniformly positive in the cytoplasm of luminal neoplastic cells in ACCs (15/15, 100%). Positive reactivity was also identified in the majority of PLGAs (16/17, 94%), with at least 25% of the tumor cells being positive. Similar reactivity was seen in monomorphic adenomas (16/17, 94%). Conclusions. In contrast to previous reports, we find that c-kit expression was not restricted to ACC but was expressed in all 3 tumor types evaluated (ACC, PLGA, and monomorphic adenoma). Therefore, c-kit does not appear to be a useful marker for distinguishing between either ACC and PLGA in equivocal cases, or in benign and malignant salivary gland neoplasms

Assessment of p63 expression in the salivary gland neoplasms adenoid cystic carcinoma, polymorphous low-grade adenocarcinoma, and basal cell and canalicular adenomas

Purpose The purpose of this study was to determine the extent of p63 immunoreactivity in the malignant salivary gland neoplasms adenoid cystic carcinoma (ACC) and polymorphous low-grade adenocarcinoma (PLGA) and to compare this to the expression of this marker in the benign salivary gland tumors canalicular adenoma and basal cell adenoma. Few studies on the expression of p63 in head and neck salivary gland tumors have been published to date. P63, a selective immunohistochemical marker of basal/stem cells of stratified epithelium and of myoepithelial cells, is a p53 homologue that plays an essential role in both morphogenesis of epidermis and limb development. P63 immunoreactivity has been demonstrated in squamous cell and urothelial carcinomas. It is generally absent in most nonsquamous cell carcinomas. Study design Formalin-fixed paraffin-embedded sections from 49 salivary gland neoplasms, representing 6 canalicular adenomas, 11 basal cell adenomas, 17 PLGA and 15 ACC accessioned from 1989 to 2002 by the Department of Pathology, Long Island Jewish Medical Center, New Hyde Park, NY, were stained with an anti-p63 monoclonal antibody. Results Nuclear p63 reactivity was uniformly positive in PLGA (17/17, 100%). Positive reactivity was also identified in the majority of cases of ACC (13/15, 87%), primarily in the nonluminal myoepithelial-like cells surrounding luminal cells. Canalicular adenoma did not exhibit any p63 immunoreactivity. All basal cell adenomas of parotid origin stained strongly for p63, with staining localized to the peripheral tumor cells situated adjacent to the connective tissue stroma. None of the basal cell adenomas originating in the upper lip stained with p63. In native adjacent salivary gland tissue, p63 reactivity was identified focally in the nuclei of myoepithelial and basal duct cells. Conclusions P63 is strongly expressed in basal cell adenoma of parotid origin, and in ACC and PLGA. Canalicular adenoma did not demonstrate p63 staining, consistent with this tumor's putative luminal ductal cell differentiation. Our results suggest that the neoplastic cells in PLGA may represent either a population of p63-positive epithelial stem/reserve cells similar to the basal cells of stratified epithelium, or modified myoepithelial cells. Given the staining pattern of the tumors examined, p63 does not appear to be an ideal marker for distinguishing between ACC, PLGA, and basal cell adenoma

Bilateral Central Giant Cell Granulomas of the Mandible in An Eight Year-Old Girl with Noonan Syndrome (Noonan-Like/Multiple Giant Cell Lesions Syndrome)

A number of conditions can present with lesions that histologically are indistinguishable from the central giant cell granuloma (CGCG) of bone, including brown tumors of hyperparathyroidism, cherubism, and, less commonly, a number of inherited syndromes. We report a case of an eight-year girl who presented with bilateral CGCGs of the posterior mandible. Characteristic facial features, reported increased post-operative bleeding and history of pulmonary stenosis led us to suspect a diagnosis of Noonan syndrome. A medical geneticist confirmed this on further evaluation. This case report will discuss the salient features of this diagnosis