“Teardrop,” “comet,” and “bowling‐pin” cells in a hobnail variant of papillary thyroid carcinoma fine needle aspirate

Abstract

Diagnostic Cytopathology. 2019;47:839-842.wileyonlinelibrary.com/journal/dc dows"), all reminiscent of mesothelial cells. Some of the peripheral cytoplasmic blebs were larger, appeared to separate from the cell bodies by thin pale lines, and resembled the apical cap ("snout") of apocrine cells; similar-sized cytoplasmic fragments were seen in the background. Mitotic figures were easily identified. The smear background showed scant colloid, numerous red blood cells, granular debris and occasional plasma cells, neutrophils, eosinophils, and lymphocytes. Based on these cytologic findings, a diagnosis of papillary thyroid carcinoma (PTC) with hobnail features was rendered. The ensuing total thyroidectomy and lymph node dissection showed a 5.3 cm PTC involving the entire thyroid, without extrathyroid extension, metastatic to six cervical and mediastinal lymph nodes. Most of the tumor had features of the hobnail variant of PTC (HVPTC; Figure 5A-D); minor components (less than 10% each) of classical, follicular, and tall cell variant were also present, as was a small area showing rhabdoid morphology. The hobnail variant of PTC (HVPTC) was described in 2010 1 as a rare aggressive variant of PTC and is included in the current WHO classification of thyroid tumors 2 and the updated Bethesda system for reporting thyroid cytopathology 3 . This variant, which constitutes 0.2% to 1.7% of PTC, is defined as nonsolid PTC with more than 30% of neoplastic cells with hobnail features and less than 10% tall cell, columnar cell or diffuse sclerosing features. 4 It has a papillary architecture, with papillae lined by crowded pseudostratified cuboidal to columnar cells with eosinophilic cytoplasm that have lost their polarity; their normally basally located nuclei are pushed to the middle of the cell or to the apical pole, appearing to be bulging out. Concomitantly, there is loss of cohesion and formation of micropapillary structures devoid of fibrovascular cores. The HVPTC is associated with older age, female sex, larger tumors, more frequent multifocality, extrathyroidal extension, vascular invasion, lymph node, and distant metastases, presence of foci of necrosis and of anaplastic carcinoma, 5 and poor prognosis. It shows positivity for cytokeratins (CK AE1/3, CK 7, CK 19), EMA, thyroglobulin, PAX8, TTF1, HBME-1, and increased p53 (25%) and Ki67 (5%-10%) staining and frequently harbors BRAFV600E mutations (rarely coexisting with TERT mutations), p53 mutations and occasionally RET/PTC1 rearrangements. 6,7 FNA cytologic features of HVPTC 8-12 include hypercellularity with cells arranged in papillary/micropapillary clusters with a variable proportion of single cells; the cells are elongated, have well-defined cell borders, apically placed "bulging" nuclei and cytoplasmic tails, imparting them a "comet" or "teardrop" appearance. The nuclei are enlarged, moderately to markedly pleomorphic and hyperchromatic and may show prominent nucleoli; nuclear grooves and intranuclear inclusions are rare. Despite these nuclear features which are unusu...

Molecular Pathology of Non-familial Follicular Epithelial–Derived Thyroid Cancer in Adults: From RAS/BRAF-like Tumor Designations to Molecular Risk Stratification

“…Summary of the major clinico-pathological and molecular characteristics of columnar cell variant of PTC* ,106,107], in contrast, distant metastases to lung, bone, liver, brain, soft tissue, and/or nasopharynx, which reflect angioinvasion, have been reported in 23.2% of cases[85, 87, 88, 90-93, 99, 101, 102, 104, 106]. From 11 publications with appropriate follow-up, 10.5% of patients died of the disease[85,87,88,91,92,99,[101][102][103][104]106].…”

Hobnail Papillary Thyroid Carcinoma, A Systematic Review and Meta-Analysis

“…After screening by title and abstract, 47 articles were left for full text review. Out of these, 29 articles fulfilled the criteria and could be included in our systematic review [ 11 , 12 , 13 , 14 , 15 , 16 , 19 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ] ( Figure 1 ).…”

Hobnail subtype of papillary carcinoma of the thyroid—a rare case with uncommon features

“…Cytomorphological diagnosis of the hobnail subtype of PTC is very difficult due to rare occurrence, paucity of literature mentioning the diagnostic features, and the diagnostic mimickers. The characteristic cytomorphology has been reported in a few cases recently 3–7 . It is also important for the further surgical management of the case.…”

“…Cytological diagnosis of the hobnail subtype is challenging due to its rarity and few authors have mentioned the characteristic features 3–7 . The clinicopathological review (with corresponding cytological and histopathological diagnosis) of the hobnail subtype of PTC is mentioned in Table 1 4–6,11–15 .…”