• fine needle
• salivary gland
• sebaceous adenoma
• sebaceous lymphadenoma

Unicystic mucoepidermoid carcinoma (UC-MEC) is a rare MEC variant, and its diagnosis is frequently problematic. This study is aimed at summarizing its clinicopathologic characteristics, treatment, and prognosis and proposing key points to avoid missed diagnosis and misdiagnosis in clinical and pathological conditions. This retrospective study included 30 UC-MEC cases, and the clinical findings were collected from the clinical medical records. Radiographic features, histologic behaviors, MAML2 rearrangement by fluorescence in situ hybridization (FISH), and follow-up data were analyzed. Moreover, glandular odontogenic cyst (GOC) and cytadenoma (CA) were used as controls. In the UC-MEC group, 19 patients were female (63%), and 11 were male (37%). The mean patient age was 39.5 (range, 7–72 years). The affected locations included the jaw (8 maxillary, 3 mandibular) and salivary glands (7 parotid, 11 palates, and 1 floor of the mouth). The chief complaint was swelling; the lesions were all cystic, among which 66.7% were well circumscribed and 33.3% poorly defined. Microscopic examination showed two UC-MEC histologic subtypes. Type A presented as a single cyst with mural thickening (8/30, 27%) lined predominantly by epidermoid cells with interspersed intermediate and mucinous cells, and type B (22/30, 73%) showed infiltrative tumor islands in the cystic wall or the surrounding tissue. FISH analysis suggested that approximately 66.7% of UC-MEC harbored a MAML2 rearrangement. During the median follow-up period of 42 months (range, 6–120 months), all type A patients and 68% of type B patients who underwent complete surgical resection lived without relapse. Seven cases with type B cancer that underwent curettage initially had local recurrence. Clinicians and pathologists hardly recognize UC-MEC owing to its cystic architecture. Specific epidermoid, mucous, and intermediate tumor cells, and MAML2 fusion testing, are essential to avoid potential diagnostic pitfalls. Prompting and completing resection surgery with negative margins would have a favorable prognosis.

• Milan classification
• cytopathology
• fine needle
• mucoepidermoid carcinoma
• salivary gland neoplasm

Salivary gland tumors are relatively uncommon with most being benign. When diagnosed the most common benign and malignant tumors are pleomorphic adenoma and mucoepidermoid carcinoma (MEC), respectively. However, not uncommonly, it is difficult to differentiate between the histopathological entities, leading to a diagnostic dilemma that can impact a patient’s treatment and prognosis. A 24-year-old woman presented with a three-year history of asymptomatic left-sided facial swelling. She denied any prior history of head and neck radiation. There was no history of alcohol consumption or smoking exposure and there was no personal or family history of head and neck cancers. Additionally, she did not have any known occupational or environmental exposures. Due to the chronicity and painless nature of this facial mass, our patient did not pursue evaluation initially. Subsequently, she experienced an increase in size and pain for a few months exacerbated by swallowing. She had no other symptoms. On physical examination, a 3 x 3 cm left parotid gland mass was noted. There was no associated head or neck lymphadenopathy and compression of the left facial mass did not elicit secretions from the opening of Stensen’s duct. Due to the rapid increase in size, she was sent for CT neck/soft tissue with contrast which confirmed a 3.56 x 2.67 cm solid nodule within the superficial portion of the left parotid gland. This was followed by an MRI orbit/face/neck with and without contrast, for further delineation, which demonstrated a 4 x 3.7 x 3 cm complex heterogeneous mass within the superficial left parotid gland. Thereafter the patient underwent an uncomplicated ultrasound-guided biopsy of the parotid mass. The histopathological appraisal concluded that this was a cellular pleomorphic adenoma, with mucinous and squamous metaplasia with reactive lymph nodes. Due to the new rapid increase in size and intense painful nature of this tumor, nerve-sparing left parotidectomy, fat grafting and reconstruction were completed. Cellular pleomorphic adenomas are benign low-grade neoplasms, typified as biphasic with both epithelial and myoepithelial components. However, they have increased cellularity and focally increased mitotic activity, not advanced enough to qualify as malignant. The presence of mucinous and squamous metaplasia is of diagnostic interest as it makes diagnosis on fine-needle aspiration (FNA) morphologically challenging. These findings are typical of MEC and on FNA can be misleading in the setting of a pleomorphic adenoma. However, on histopathological evaluation of the gross specimen along with immunohistochemical staining the diagnosis is made much easier. A diagnosis of MEC would have potentially required neck dissection and adjuvant therapy with a potential increased risk of morbidity and mortality. This case emphasises the importance of an adequate tissue biopsy in regards to parotid gland tumors to optimise a patient's care plan.

• biphasic tumor
• enucleation
• enucleoresection
• fine needle aspiration cytology (fnac)
• mucoepidermoid carcinoma
• pleomorphic adenoma

• cytology and cytopathology
• fine needle aspiration
• pleomorphic adenoma
• secondary change
• xanthogranulomatous change

Pleomorphic adenoma (PA) is the most common benign tumor of major or minor salivary glands. PA exhibits a great histological diversity, such as differentiation into oncocytic, sebaceous, mucinous, squamous, chondroid, osseous or adipose cells. Squamous metaplasia rarely results in the formation of extensive keratin-filled cyst lined by squamous epithelium. Extensive squamous metaplasia can be mistaken for malignancy, including mucoepidermoid carcinoma and squamous cell carcinoma. Here, we report a case of slowly enlarging PA with extensive squamous metaplasia and keratin cyst formations in a minor salivary gland in hard palate and discuss its microscopic features.

• Keratin
• pleomorphic adenoma
• squamous metaplasia

Definitive diagnosis of parotid gland masses is required optimal management planning and for prognosis. There is controversy over whether fine needle aspiration cytology (FNAC) or ultrasound guided core biopsy (USCB) should be the standard for obtaining a biopsy. The aim of this review is to assess the current evidence available to assess the benefits of each technique and also to assess the use of intra-operative frozen section (IOFS). Literature searches were performed using pubmed and google scholar. The literature has been reviewed and the evidence is presented. FNAC is an accepted and widely used technique. It has been shown to have variable diagnostic capabilities depending on centres and experience of staff. USCB has a highly consistent diagnostic accuracy and can help with tumour grading and staging. However, the technique is more invasive and there is a question regarding potential for seeding. Furthermore, USCB is less likely to be offered as part of a one-stop clinic. IOFS has no role as a first line diagnostic technique but may be reserved as an adjunct or for lesions not amenable to percutaneous biopsy. On balance, USCB seems to be the method of choice. The current evidence suggests it has superior diagnostic potential and is safe. With time, USCB is likely to supplant FNAC as the biopsy technique of choice, replicating that which has occurred already in other areas of medicine such a breast practice.

• Parotid
• Biopsy
• Fine needle aspiration cytology
• Mass
• Fine needle aspiration
• Cytology
• Core-biopsy
• Ultrasound
• Diagnosis

• Adenocarcinoma, Mucinous/pathology
• Adenoma, Pleomorphic/pathology
• Adult
• Biopsy, Fine-Needle
• Carcinoma, Squamous Cell/pathology
• Diagnosis, Differential
• Humans
• Male
• Metaplasia
• Parotid Gland/pathology
• Parotid Neoplasms/pathology

• Histological diversity
• Parotidectomy
• Salivary gland neoplasms

• fine needle aspiration cytology
• neoplasia
• parotid
• ultrasound-guided core biopsy

• fine needle aspiration
• pleomorphic adenoma
• salivary gland lesions
• tumor tract seeding
• ultrasound-guided core biopsy

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Biopsy, Fine-Needle
• Biopsy, Needle
• Female
• Humans
• Male
• Middle Aged
• Parotid Diseases/diagnosis
• Parotid Gland/pathology
• Parotid Neoplasms/diagnosis
• Sensitivity and Specificity
• Ultrasonography, Interventional
• Young Adult

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.

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.

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.

• Mucoepidermoid carcinoma
• pleomorphic adenoma
• squamous metaplasia

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Biopsy, Needle/methods
• Female
• Humans
• Male
• Middle Aged
• Parotid Neoplasms/diagnostic imaging
• Parotid Neoplasms/pathology
• Reproducibility of Results
• Sensitivity and Specificity
• Ultrasonography, Interventional/methods

• Biopsy/methods
• Biopsy, Fine-Needle/methods
• Diagnosis, Differential
• Humans
• Parotid Diseases/pathology
• Parotid Neoplasms/pathology
• Patient Selection
• Sensitivity and Specificity
• Ultrasonography, Interventional

• Adenoma, Pleomorphic/diagnosis
• Adenoma, Pleomorphic/pathology
• Aged
• Biopsy, Fine-Needle
• Carcinoma, Mucoepidermoid/diagnosis
• Carcinoma, Mucoepidermoid/pathology
• Cell Differentiation
• Humans
• Male
• Neoplasms, Adnexal and Skin Appendage/diagnosis
• Neoplasms, Adnexal and Skin Appendage/pathology
• Salivary Gland Neoplasms/diagnosis
• Salivary Gland Neoplasms/pathology
• Salivary Glands/pathology