Palatal pleomorphic adenoma with florid squamous metaplasia: a potential diagnostic pitfall

Pleomorphic Adenoma with Extensive Squamous and Adipocytic Metaplasia Mimicking as Low Grade Mucoepidermoid Carcinoma on FNAC

Pleomorphic adenoma (PA) is the most common salivary gland tumor, accounting for 54-76% of all salivary gland neoplasms. Extensive squamous metaplasia in PA can be mistaken for malignancy, including low grade mucoepidermoid carcinoma and squamous cell carcinoma. Here, we present an unusual case of PA with extensive squamous metaplasia and keratin cyst formations in a minor salivary gland, and discuss its microscopic features, including the immunohistochemical characteristics, and differential diagnosis of this uncommon presentation.

Pleomorphic adenoma: the great mimicker of malignancy

Pleomorphic adenoma (PA) is the most common salivary gland neoplasm, and its diagnosis is straightforward in the majority of cases. However, not infrequently, PA shows unusual and uncommon histological features that can be confused with those of malignancy. The difficulties in diagnosing PA arise from its ability to mimic invasion, show atypical or metaplastic cytomorphology, and show morphological features that overlap with those of established salivary gland carcinomas. In addition, recognising early malignant transformation to carcinoma ex-pleomorphic adenoma continues to be a frequent challenge. This review describes the diagnostic pitfalls of PA, and offers a systematic approach to avoid them by combining classic histopathology with novel immunohistochemical and molecular tests.

Pleomorphic Adenoma in the Lower Lip: A Case Report and a Review

Pleomorphic adenoma constitutes 50% of salivary gland tumors affecting mostly the parotid gland extraorally, and the palate intraorally. While the upper lip is a common site, it is unusual to encounter this tumor in the lower lip. A 26-year-old man complained of a persistent lump affecting the lower lip. The lesion was excised and was shown on histopathological examination to be a pleomorphic adenoma with squamous metaplasia. At the 18-month review appointment, there was complete healing and no recurrence. Pleomorphic adenoma in the lower lip should be considered among the differential diagnosis of lower labial swellings, especially in young patients. There needs to be reconsideration of the epidemiological and histological characteristics.

Pleomorphic adenoma: a rare presentation in buccal salivary gland with extensive squamous and mucous metaplasia

Pleomorphic Adenoma (PA) is the most common salivary gland tumor and accounts for about 60% of all salivary gland neoplasms. Intraorally, the hard palate is the most common presenting site (50-60%) followed by upper lip (15-20%) and rarely buccal mucosa (8-10%). Histopathologically, PA shows diverse morphology resulting from amalgamation of cellular and stromal components. The PA may show changes in the stromal and epithelial components, such as sebaceous, lipocytic and oncocytic metaplasia. A rare characteristic of PA is to show extensive squamous and mucous differentiation which poses diagnostic dilemma to the pathologist. Here, we present an unusual case of PA of buccal minor salivary gland with squamous and mucous metaplasia. The localization, gender and microscopic features of the presented case are unusual.

Squamous Metaplasia in Pleomorphic Adenoma: A Diagnostic and Prognostic Enigma

Pleomorphic adenoma (PA) is the most common benign salivary gland tumor. Histologically, squamous metaplasia has been reported in PA, but has rarely been documented as being extensive enough to cause significant misdiagnosis. Here, we present an unusual case of PA in a 50-year-old female patient presenting with swelling on the postero-lateral aspect of the palate for a week. Histopathologically, the tumor exhibited the features of conventional PA with extensive squamous metaplasia and giant keratotic lamellae in cyst-like areas. Such exuberant squamous metaplasia and keratin can be a diagnostic and prognostic pitfall and lead to overtreatment of the patient.

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.

A challenging case of squamous metaplasia in a pleomorphic adenoma: diagnostic and clinical pitfalls

Squamous metaplasia in a pleomorphic adenoma (PA) has been reported, but rarely has it been documented as being extensive enough to cause significant misdiagnosis. We present a case of a 37-year-old man presenting with a 1.7-cm minor salivary gland PA of the palate. It exhibited extensive squamous metaplasia mimicking a squamous cell carcinoma (SCC) on multiple preoperative biopsies. The final diagnosis was only made after a complete oncological excision with margins and free flap reconstruction. Florid squamous metaplasia in a PA, although rare, should be recognized and distinguished from SCC. Failure to differentiate these entities can lead to patient overtreatment.

A benign salivary gland tumor of minor salivary gland mimicking an epithelial malignancy

Pleomorphic adenoma (PA) is the most common benign tumor of major or minor salivary glands. Microscopically, PA exhibits a great diversity of morphological aspects. Here, we present an unusual case of PA with extensive squamous metaplasia and keratin-filled cysts in the left retromolar region of a 50-year-old edentulous person whose microscopic finding may represent a diagnostic dilemma for pathologists.

Schwannoma-like pleomorphic adenoma of the parotid

Pleomorphic adenoma is the most common benign salivary gland tumour. It can occur in any salivary gland, but is most frequently found in the parotid gland. Chondroid metaplasia is a frequent finding in pleomorphic adenoma. Other forms of metaplasia have been described, but are encountered less frequently. We report a rare case of unusual pleomorphic adenoma of the parotid gland with schwannoma-like feature.

Pleomorphic adenoma with squamous and appendageal metaplasia mimicking mucoepidermoid carcinoma on cytology

Background:

Histological diversity is the hallmark of pleomorphic adenoma, the most common salivary gland tumor. It may cause difficulty in cytological interpretation, due to limited and selective sampling.

Case presentation:

A 16-year-old female patient presented with right cheek swelling. Fine needle aspiration cytology showed squamous cells, basaloid cells, and foamy cells, along with extracellular keratin and foreign body giant cells. Characteristic metachromatic fibrillary chondromyxoid stroma, which is usually seen in pleomorphic adenoma, was not seen in the aspirate. A diagnosis of mucoepidermoid carcinoma was given on cytology. Subsequent resection revealed an encapsulated pleomorphic adenoma, with extensive squamous metaplasia and appendageal differentiation on histology.

Conclusion:

This case illustrates that pleomorphic adenoma with squamous metaplasia presents a potential for misinterpretation as mucoepidermoid carcinoma on cytology. We discuss the various pitfalls and the features that are helpful in distinguishing these two lesions.

Pleomorphic adenoma of the submandibular gland: an evolving change in practice following review of a personal case series

We reviewed patients with submandibular gland pleomorphic adenoma treated at a tertiary referral centre in the United Kingdom (1988-2004). Thirty-seven patients were identified, 32 newly diagnosed cases and 5 cases of recurrent disease previously treated elsewhere. The exact pre-operative diagnosis was "unknown" in 76% of the new cases. All cases were surgically excised (41% with extracapsular gland excision and 59% by selective level Ib, IIa and III neck dissection). Temporary marginal mandibular nerve neuropraxia was documented in 25% of cases. All 32 new cases remain clinically tumour free at the time of writing. In patients with recurrent disease, complete microscopic tumour clearance was achieved in three of the five cases, however all remain clinically tumour free. Pleomorphic adenomas of the submandibular gland are uncommon, with good prognosis following complete tumour excision. Recurrent tumours, however, are frequently multi-focal and difficult to excise completely. The adequacy of primary surgery is crucial and supports an approach for a more radical excision primarily by a selective level lb, IIa and III neck dissection; ensuring complete disease clearance for pleomorphic adenoma, avoiding the risks of tumour spillage associated with a limited excision and tumour handling; and removing the primary echelon of lymph nodes at risk of metastasis if the pathology turns out to be malignant.

Differential diagnosis between adenoid cystic carcinoma and pleomorphic adenoma of the minor salivary glands of palate

Tumors arising from minor salivary glands of the palate may exhibit an overlap of clinical and biologic features that may produce diagnostic and therapeutic dilemmas. Surgical treatment can be very different, depending on the dimensions and malignant or benign nature of the tumors, and therefore should be planned on the basis of an accurate differential diagnosis. A retrospective analysis in 24 patients with pleomorphic adenoma and adenoid cystic carcinoma of minor salivary glands of the palate was performed to investigate the accuracy of fine needle aspiration cytology (FNAC) and biopsy with histology in the preoperative diagnosis. Preoperative diagnoses obtained with FNAC and biopsy were compared with findings of the definitive histopathologic examination performed on the resected mass. Correspondence between the preoperative diagnoses determined by FNACs and the definitive histopathologic results was observed in 22 of 24 cases, whereas a complete equivalence was found with regards to histology. In the analysis, FNAC was associated with 91.6% accuracy and an error rate of 8.4% in the diagnosis of pleomorphic adenoma and adenoid cystic carcinoma of the palate. From the results of the analysis, histologic examination is still the most accurate diagnostic tool in such tumors. FNAC can be considered in tumors of the head and neck regions that are difficult to reach by means of a common biopsy.

Pleomorphic adenomas of the lacrimal gland: a clinicopathological analysis

PURPOSE

To analyse retrospectively 32 cases of pleomorphic adenoma of the lacrimal gland diagnosed over a 10-year period in a tertiary referral eye centre from North India.

METHODS

The clinical features of 32 cases of pleomorphic adenomas diagnosed between 1991 and 2000 were analysed and the histopathological features reviewed light microscopically.

RESULTS

Among the clinical features, a marked male predominance with younger age of presentation and left-sided dominance was noted. The duration of symptoms was less than 10 months in 28% cases. Histopathologically, the features included presence of cystic degeneration (15.6%) and squamous metaplasia (18.7%). Calcification, osteoid formation and malignant transformation (3.1% each) were occasionally observed.

CONCLUSIONS

Pleomorphic adenomas of the lacrimal gland may present with duration of symptoms of less than 10 months. Cystic degeneration, squamous metaplasia, calcification or ossification may be observed in lacrimal gland pleomorphic adenomas, as has been described in pleomorphic adenomas of salivary glands. However, the presence of calcification and bone erosion radiologically in a lacrimal gland tumour does not necessarily indicate malignancy.

Worrisome histologic alterations following fine-needle aspiration of benign parotid lesions

OBJECTIVE

To describe the histologic changes associated with preoperative fine-needle aspiration biopsies of benign parotid lesions and the features that distinguish these changes from malignant neoplasms.

MATERIALS AND METHODS

Ten benign parotid lesions with a recent history of preoperative fine-needle aspiration were selected, including pleomorphic adenoma (4 cases), oncocytic adenoma (3 cases), myoepithelioma (1 case), Warthin tumor (1 case), and lymphoepithelial cyst (1 case).

RESULTS

A spectrum of histologic alterations were observed. Alterations included squamous cell metaplasia (8 cases), infarction and necrosis (4 cases), subepithelial stromal hyalinization (3 cases), acute and chronic hemorrhage and inflammation with multinucleated giant cells (all cases), granulation tissue with subsequent fibrosis (all cases), cholesterol cleft formation (1 case), pseudoxanthomatous reaction (1 case), pseudocapsular invasion (1 case), and microcystic degeneration (2 cases). In cases with exuberant squamous metaplasia, necrosis, or subepithelial stromal hyalinization, a diagnosis of squamous cell carcinoma or low-grade mucoepidermoid carcinoma was seriously considered.

CONCLUSIONS

Knowledge of a previous fine-needle aspiration procedure and awareness of its effects on histology of the subsequent parotidectomy specimens are necessary to avoid potential misdiagnosis.