The institutional frequency of NIFTP histopathology diagnosis and cytology baseline data will impact the ROM associated with specific FNAC diagnoses, especially among the indeterminate TBSRTC categories. The range of ROM for each TBSRTC diagnostic category is reflective of the inherent diagnostic thresholds and interobserver and interinstitutional variability in the diagnosis of thyroid lesions. Cancer Cytopathol 2018;126:20-6. © 2017 American Cancer Society.

Synovial sarcomas (SS) of the head and neck region are extremely rare and arise in only 5% of cases. We present a case of secondary SS of the thyroid originally diagnosed as medullary carcinoma on fine needle aspiration (FNA). A 41-year-old man presented with several weeks of dysphonia and a left thyroid mass. FNA of the thyroid nodule showed a cellular smear composed of loosely cohesive oval to spindle-shaped cells with irregular nuclear borders, finely granular chromatin, and inconspicuous nucleoli. The patient was diagnosed with medullary carcinoma and underwent a total thyroidectomy. Intro-operatively, the mass was found to arise from the tracheoesophageal groove with spread to the left thyroid. Microscopic examination of the thyroid tumor revealed a dense spindle cell proliferation with abundant mitoses, scant cords and nests of epithelial cells and foci of necrosis. The spindle cells were positive for bcl2 and vimentin and the epithelial cells were positive for cytokeratin 8/18 and epithelial membrane antigen (EMA). Both spindle and epithelial cells were negative for thyroglobulin, calcitonin, synaptophysin and chromogranin. Fluorescence in situ hybridization (FISH) demonstrated translocation (X;18)(p11;q11), confirming the diagnosis of SS. The patient underwent a total laryngopharyngoesophagectomy with subsequent adjuvant therapy and is currently disease free. Only 6 cases of histologically confirmed primary SS of the thyroid have been reported. To the best of our knowledge, this is the first case of FISH-confirmed secondary SS of the thyroid and also the first case of SS arising from the tracheoesophageal groove.

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Adenomyoma or adenomyomatosis (ADM) of the gallbladder generally carries little or no risk of malignant transformation. Rare cases of such malignant transformation are described in the literature only in segmental type of ADM and not in localized adenomyoma. We report a case of a 58-year-old asymptomatic woman found to have an incidental 3.3 × 3.2 × 2.3 cm well-circumscribed exophytic mass on surveillance ultrasound, originating from the fundus of the gallbladder and abutting the liver capsule. The patient underwent an open cholecystectomy with resection of the mass and underlying segment of the liver. The mass was discrete and well-circumscribed with a peripheral pseudocapsule. Histologically, it showed features typical of a benign adenomyoma with variably sized distended microcysts within fibromuscular stroma. Within the lesion, however, multiple small foci amounting to approximately 5% of the total lesion showed high-grade dysplasia or adenocarcinoma in situ. Apart from cytological distinctiveness, these foci were also selectively highlighted by positive immunostaining for p53 and higher Ki-67 reactivity. Away from this lesion, the gallbladder showed cholelithiasis, mild cholecystitis, and no additional adenomyoma. There was no invasion into the gallbladder mucosa or adjacent liver. This case is highly unusual since transformation to carcinoma is not previously described in a localized or discrete adenomyoma. In the short available follow-up (4 months to date), there is no evidence of recurrence or metastasis. The long-term prognosis is expected to be favorable due to lack of invasion and complete excision, even if there is no documented literature regarding its course.