Pleomorphic adenoma with extensive necrosis: report of two cases

Pleomorphic Adenoma with a Novel Gene Rearrangement-LINC01606::PLAG1

BACKGROUND

Pleomorphic adenoma is a well-known benign salivary gland neoplasm characterized by the presence of varying proportions of three different components, including bi-layered ducts, myoepithelial cells, and admixed within a chondromyxoid/fibrous stroma.

METHOD

We report an interesting case of an adult male who presented with bleeding from an extensively degenerated parotid gland mass, concerning for a vascular neoplasm versus primary malignant tumor. Microscopically, majority of the viable tumor exhibited diffuse proliferation of spindle to epithelioid cells, with focal areas depicting cribriform glands, ducts, and scant chondromyxoid stroma.

RESULT

Next-generation sequencing (NGS) RNA-based fusion panel analysis identified a gene rearrangement involving the pleomorphic adenoma gene 1 (PLAG1), with a novel, cryptogenic fusion partner known as LINC01606; [LINC01606::PLAG1; inv(8;8)(8q12.1;8q12.1)].

CONCLUSION

To the best of our knowledge, this is the first documented case of a long non-coding RNA (lnc-RNA) serving as a rearrangement partner with the PLAG1 gene. We reviewed the molecular characteristics of this entity and explored the potential role of LINC01606::PLAG1 in the tumorigenesis of pleomorphic adenoma.

Cystic lesions in the salivary gland. Pitfalls to be avoided on cytology

Cystic lesions of the salivary glands are very uncommon entities. However, on occasion, some neoplasms of the salivary glands show a cystic component, which may be predominant or only partially cystic. Basal cell adenoma, canalicular adenoma, oncocytoma, sebaceous adenoma, intraductal papilloma, epithelial-myoepithelial carcinoma, intraductal carcinoma, and secretory carcinoma are such cystic entities. Cystic degeneration and necrosis, which can develop within solid tumours, represent another possibility. The ability to recognise this type of lesion is a challenge in diagnostic cytology because hypocellular fluid is frequently recovered. Furthermore, evaluating all of the differential diagnoses for cystic lesions of the salivary glands is helpful in obtaining the correct diagnosis. Herein, we evaluate the various types of cystic lesions within the salivary glands.

Extensive Sclerosis ("mummification") in Lacrimal Gland Pleomorphic Adenoma May Indicate Neighboring Malignant Transformation

Salivary gland pleomorphic adenomas not uncommonly show extensive sclerosis ("dense hyalinization," "coagulative necrosis," or "mummification"), which arise spontaneously or after prior surgery, and this change is considered a high-risk factor for malignant transformation of benign salivary adenomas. While minor hyalinization is common in lacrimal gland adenomas, massive sclerosis-where almost all (90% or more) of the tumor is replaced by an amorphous hyaline material-is extremely rare. Four patients (2 males) are described in whom, despite not having an acute inflammatory episode, their lacrimal gland tumor showed marked sclerotic necrosis within the majority of either the benign or malignant parts of the tumor. Three tumors had evidence of malignant change, 2 to adenocarcinoma, and 1 to mucoepidermoid carcinoma, but none of the malignant areas showed perineural or endovascular invasion. Extensive sclerosis in association with a lacrimal gland pleomorphic adenoma (LGPA) is rare (4/110 of the cases) and-as with salivary adenomas-appears to be associated with a high chance of associated malignant change. Both the surgeon and the histopathologist should regard extensive sclerotic necrosis as a harbinger for malignant change in association with benign pleomorphic adenomas of the lacrimal gland.

Lacrimal gland pleomorphic adenoma with extensive necrosis

Lacrimal gland pleomorphic adenomas (LGPA) are benign mixed tumors. Diagnosis is based on clinical and radiological findings which usually prompts complete excision of the lesion to minimise recurrence and a cumulative risk of malignant transformation. Necrosis in pleomorphic adenoma has been rarely reported in salivary gland PA, either spontaneously or due to iatrogenic interventions. Necrosis is suggestive of a malignant process and makes interpretation of histology specimens difficult. A 23 year old woman, while awaiting biopsy for a mass in the left lacrimal gland, which had been symptomatic for only several months, presented with acute pain and swelling of the left lateral lid. An incisional biopsy showed an inflamed lacrimal gland with focal necrosis and atypia of adjacent cytology and gland architecture. Subsequent excisional biopsy confirmed an LGPA with some inflammation but no necrosis. Necrosis may occur as an atypical presentation in LGPA.

Pleomorphic adenoma of salivary glands: common and uncommon CT and MR imaging features

Pleomorphic adenoma (PA) is the most common salivary gland tumor and is characterized by cytomorphological and architectural diversity. On CT and MR images, PAs are shown as well-defined lesions occasionally accompanied by characteristic lobulated contours. On T2-weighted images, typical PAs show marked hyperintensity, which reflects the abundant myxochondroid stroma, with a hypointense rim indicating the fibrous capsule. However, intratumoral signal intensity varies according to the cellular density, proportion of epithelial and stromal components, and type of stromal components. In addition, a variety of secondary histological changes, including fibrosis, lipometaplasia, ossification, cystic degeneration, and infarction, occur rarely in PAs; therefore, they are associated with difficulty in differential diagnosis from other salivary gland tumors. This review article describes the common and uncommon CT and MR imaging features of PA of the salivary glands.

Cystic Change in Pleomorphic Adenoma: A Rare Finding and a Diagnostic Dilemma

Pleomorphic adenoma forms the majority of salivary gland neoplasms. Cystic change in pleomorphic adenomas is a diagnostic dilemma and can mimic mucoepidermoid carcinoma, mucocele or carcinoma ex pleomorphic adenoma and squamous cell carcinoma. Hereby we report this interesting and rare case of cystic pleomorphic adenoma in a 32-year-old male.

Pleomorphic adenoma of the salivary glands in children and adolescents

BACKGROUND

Pleomorphic adenomas (PAs) of the salivary glands are rare in children and adolescents. We reviewed the clinical manifestations, pathologic features, treatment, and prognosis of salivary gland PA in 90 children and adolescents.

METHODS

Clinical data including age, sex, location, symptoms, the period of evolution of the symptoms, pathologic type, and surgical treatment were evaluated.

RESULTS

The median age was 16.5 years old. There was a 1.43:1 female-to-male ratio. The parotid gland was the most commonly affected major gland (56.7%), and the palate, the most common site of minor salivary gland involvement. Ultrasonography and computed tomography were performed in most cases for diagnosis. Superficial parotidectomy or total parotidectomy with facial nerve dissection and preservation was the most common surgical procedure. Submandibular triangle dissection was applied to all submandibular PAs. Classic-type PA was the most common histologic subtype (43.3%).

CONCLUSIONS

Salivary gland PAs in children and adolescents have different characteristics compared with their adult counterparts in regard to histologic subtype and location. Surgical removal is the best treatment option for PAs in children and adolescents.

[Cystic parotid gland lesion evaluation]

OBJECTIVES

We evaluated differential diagnoses of cystic parotid gland lesions and the efficacy of preoperative diagnosis.

MATERIALS AND METHODS

Of 191 parotid gland nodules resected between January 2003 and October 2008, 167 (87%) were benign and 24 (13%) malignant. Thirty-five parotid gland nodules whose components were almost cystic were enrolled in this study. All cystic lesions were retrospectively evaluated with respect to preoperative diagnostic examinations and histopathological confirmed diagnosis. Cystic components in surgical specimens were also evaluated histopathologically. The relationships with magnetic resonance imaging (MRI) findings and histopathological confirmed diagnosis were studied.

RESULTS

Of 35 cystic lesions, 11 were complete cystic masses and had no mural nodules, while remaining 24 were incomplete and had mural nodules. Histopathological examinations showed that 5 were nonneoplastic, 27 were cystic degenerations of benign tumors, and 3 were cystic degenerations of malignant tumors. In the 11 complete cysts, preoperative diagnosis could not be made using any modality, whether with FNAC, salivary scintigraphy, or 67-gallium citrate scintigraphy. Of 24 incomplete cysts, only 9 cystic Warthin tumors were diagnosed correctly before surgery. Studies of cystic components in MRI and histopathology suggested that hemorrhagic degeneration of malignant tumors should be kept in mind for cystic lesions showing hemorrhagic portions.

CONCLUSIONS

Cystic parotid gland lesions are difficult to diagnose correctly before surgery, but the evaluation of cystic components by MRI and FNAC is helpful in differentiating between benign and malignant tumors.