Recognition of specific morphologic patterns is an accurate method of identifying benign thyroid nodules that do not require cytologic evaluation. Use of this approach may substantially decrease the number of unnecessary biopsy procedures.

No abstract

Lesions with follicular lesion of undetermined significance-like or oncocytic features are prone to misdiagnosis. The current study identified distinct cytologic patterns in parathyroid lesions suggestive of parathyroid origin, which, together with PTH immunostains or assay, molecular studies, or sestamibi scans, aid in distinguishing parathyroid from thyroid lesions. Cancer Cytopathol 2017;125:674-82. © 2017 American Cancer Society.

Erdheim-Chester disease (ECD) is a rare multiple system histiocytosis that is characterized pathologically by xanthogranulomatous infiltrates and radiologically by symmetrical sclerosis of long bones. The diagnosis is often confirmed by biopsy of bone or of orbital or retroperitoneal soft tissue. Intracranial involvement is rare. The authors report a case of ECD in which the diagnosis was made after biopsy of a hypothalamic mass. The mass had been discovered during a workup for panhypopituitarism in a 55-year-old man with urological and bone disease. Aside from diabetes insipidus, other features of pituitary insufficiency have seldom been reported and no patients have presented with a hypothalamic tumor. The endocrinological and neurological aspects of ECD are discussed, as is its differential diagnosis. Reported cases of the disorder associated with hypopituitarism or found during biopsy of central nervous system structures are also reviewed.

Cytologic diagnosis of extra-adrenal paraganglioma presenting as a peripancreatic mass is challenging with a high error rate due to its rarity. We report two cases of peripancreatic masses identified by radiology. Endoscopic ultrasound-guided fine needle aspiration (FNA) of the masses showed a moderately cellular tumor composed of small to medium sized neoplastic cells with round to oval nuclei, arranged singly and in loose clusters. Focal rosette-like structures were present. The cells were positive for neuroendocrine markers (synaptophysin and chromogranin). A diagnosis of a neoplasm with neuroendocrine differentiation and neuroendocrine tumor was made respectively on FNA for each case. The subsequent surgical resection of the tumors revealed peripancreatic paraganglioma. Although paraganglioma has been reported in the literature, the detailed comparison of perpancreatic paraganglioma versus pancreatic/gastrointestinal neuroendocrine tumor is still lacking. Therefore using these two cases with literature review, we wish to illustrate the differential diagnosis between these two entities based on cytomorphology and immunohistochemical study.

Background Hürthle cell lesions often pose diagnostic challenges, despite their common occurrence on thyroid fine‐needle aspiration cytology (FNAC). The associated molecular alterations are also not well understood. Therefore, our study aimed to delineate the molecular profile of Hürthle cell lesions classified as Bethesda Categories III or IV (atypia of undetermined significance (AUS) or suspicious for follicular neoplasm (SFN)) on FNAC and to correlate this molecular profile with surgical resection findings. Methods This study consisted of 188 Hürthle cell lesions with indeterminate cytology and ThyroSeq® v2/v3 molecular testing results. Surgical follow‐up was available for 33 cases. Results The majority of indeterminate Hürthle cell lesions had negative ThyroSeq® results (61%) and were benign on available surgical follow‐up. The most prevalent mutations involved the RAS gene (21%), which were associated with benign lesions, non‐invasive follicular thyroid neoplasms with papillary‐like nuclear features (NIFTP), and malignancy. The remaining mutations involved less than 18% of the cases, including PAX8/PPARG (3.7%), TSHR (3.7%), EIF1AX (2.7%), MET (2.1%), PTEN (1.6%), clonal copy number alteration (1.6%), TERT (1.1%), and 0.5% each of GNAS, PIK3CA, and TP53 mutations. On follow‐up, 45% were benign, 24% were NIFTP, and 30% were malignant. The malignant cases had different molecular alterations. Conclusion No single molecular alteration defines cytologically indeterminate Hürthle cell lesions; the majority of cases have low‐risk or no molecular alterations and are benign on follow‐up. These findings suggest that molecular testing may be useful, but is not definitive, in determining which cases may be managed conservatively; additional studies are needed to fully determine the negative predictive value in ruling out malignancy.

A b s t r a c tPathologists, like radiologists, 1-5 frequently are frustrated by the absence of patient history on specimen requisition forms. At some institutions, cytologists who interpret respiratory cytology are lucky to even get the information "r/o dz [sic]." There has been little study of how this history affects pathologic diagnostic accuracy. 6,7 The importance of history partly depends on how clinicians use the pathologic diagnosis. [8][9][10]

We theorize that the stiffness of the colon in areas of collagenous colitis with submucosal fibrosis makes it susceptible to linear "fractures" during colonoscopic air insufflation with subsequent transmural air dissection. We urge extreme caution if this lesion is recognized at colonoscopy and recommend aborting the examination and obtaining plain radiographs to detect free intraperitoneal air.