Pilomatrixoma, also known as calcifying epithelioma of Malherbe, is a rare benign skin tumor originating from hair follicle matrix cells. It typically presents as a firm, painless subcutaneous nodule, most commonly found in the head, neck, and upper extremities. Pilomatrixoma can occasionally appear in atypical locations, posing a diagnostic challenge due to its nonspecific clinical presentation. A 43-year-old female presented with a painless, slowly enlarging mass on the lateral side of her left ankle, which had been present for approximately one year. Physical examination revealed a firm, well-circumscribed subcutaneous nodule measuring about 2 cm in diameter with normal overlying skin. An MRI of the left ankle demonstrated a well-circumscribed, subcutaneous mass with heterogeneous signal intensity, consistent with calcifications, suggesting pilomatrixoma. A fine-needle aspiration biopsy confirmed the presence of basaloid cells, shadow cells, and areas of calcification. The lesion was surgically excised, and histopathological examination validated the diagnosis of pilomatrixoma. The patient had an uneventful postoperative course, with no recurrence at the six-month follow-up. This case underscores the importance of considering pilomatrixoma in the differential diagnosis of subcutaneous nodules, even in unusual locations. A comprehensive diagnostic approach, including clinical evaluation, imaging, and histopathological examination, is essential for an accurate diagnosis. Surgical excision with clear margins is the treatment of choice, ensuring low recurrence rates and excellent patient outcomes. This report enhances the understanding of pilomatrixoma and highlights the necessity for a multimodal diagnostic strategy in managing this rare condition effectively.

BACKGROUND: The Ki-67 proliferative index (PI) is part of the diagnosis of nodal B-cell lymphoma (nBCL), but its determination in cytological samples is not standardized. We aimed to establish an approach for the accurate determination of the Ki-67 PI in cytological slides to differentiate between indolent and aggressive nBCLs.
METHODS: Patients diagnosed with nBCL by fine-needle aspiration biopsy and subsequent excision biopsy were included. Cell suspensions were prepared from biopsy samples for CD3/Ki-67 double immunocytochemical staining and flow-cytometric verification of lymphoma B-cell counts. The Ki-67 PI was assessed by manual counting and eyeballing in cytology and eyeballing in histology. The cut-off values for the differentiation between aggressive and indolent lymphomas were determined for each method.
RESULTS: A strong correlation between manual and flow-cytometric counting of lymphoma B cells was confirmed (interclass correlation coefficient (IC coef.) = 0.78). The correlation of the Ki-67 PI determined in cytological and histological slides was also strong (IC coef. > 0.80). Histologically, 55 cases were classified as indolent and 31 as aggressive nBCLs. KI-67 PI cut-off values of 28.5%, 27.5%, and 35.5% were established for manual counting and eyeballing in cytology and eyeballing in histology, respectively, with high sensitivity and specificity.
CONCLUSIONS: The Ki-67 PI, assessed by manual counting and eyeballing in cytological samples, accurately differentiates between indolent and aggressive nBCLs.

OBJECTIVE: Fine needle aspiration biopsy (FNAB) is currently the gold standard for diagnosis and treatment of thyroid nodules, but the growing need for anatomic pathology services in small communities is becoming a challenge. Telecytology (TC) is defined as the electronic transmission of cytological digital images, and allows for the collection of samples, primary diagnosis, and other applications without the physical presence of a pathologist. Our aim is to systematically report, summarize, and critically analyze the most up to date applications of TC to thyroid nodules FNAB evaluation.
METHODS: We performed a systematic literature review by searching PubMed, Embase, and Cochrane Library databases. Only studies published in peer-reviewed scientific journals were included. Data were extracted using the PICO framework and critically analyzed. PRISMA guidelines were applied, and the risk of bias in the included studies was assessed using the ROBINS-I tools. The methodological quality was assessed following GRADE criteria.
RESULTS: We included 13 observational studies, resulting in a total of 3856 evaluated FNAB specimens. The majority of studies (63.6%) showed an excellent concordance rate of diagnosis via TC and conventional cytology. TC can be used to perform preliminary assessment of samples with a concordance rate ranging from 74 and 100%, showing a significant reduction of the non-diagnostic rate. Image quality was referred to as perfect or nearly perfect in most cases, regardless of telecytology technique.
CONCLUSIONS: Telecytology could be a valuable implementation for thyroid FNAB evaluation both for primary diagnosis and preliminary assessment of samples.

To avoid unnecessary surgeries, ultrasound-guided fine-needle aspiration biopsy (FNAB) is an effective and reliable procedure for the preoperative evaluation of thyroid nodules. However, there have been only a limited number of studies exploring the ability of preoperative FNAB to distinguish malignancy compared to postoperative histopathology in thyroid nodules larger than 4 cm. The aim of this study was to investigate the diagnostic accuracy of FNAB compared to postoperative histopathology in distinguishing malignancy in thyroid nodules larger than 4 cm. A single-center retrospective observational study was conducted at Dr. Zainoel Abidin Hospital, Banda Aceh, Indonesia, between January 2014 and December 2018. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated. A total of 83 patients were included in the study. The results showed that preoperative FNAB may have the ability to distinguish malignancy compared to postoperative histopathology. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 42.85%, 98.38%, 90.00%, 83.56%, and 84.33%, respectively. These data suggested that ultrasound-guided preoperative FNAB is a reliable diagnostic tool in the preoperative evaluation of thyroid nodules larger than 4 cm, but it has limited capability in distinguishing malignancies. In conclusion, although FNAB may be useful in reducing unnecessary surgeries, histopathology remains the preferred method for confirming malignancy in thyroid nodules.

BACKGROUND: To compare conventional smears (CSs) and liquid-based preparations (LBPs) for diagnosing thyroid malignant or suspicious lesions.
METHODS: Studies in the PubMed, SCOPUS, Embase, Web of Science, and Cochrane database published up to December 2023. We reviewed 17 studies, including 15,861 samples.
RESULTS: The diagnostic odds ratio (DOR) for CS was 23.6674. The area under the summary receiver operating characteristic curve (AUC) was 0.879, with sensitivity, specificity, negative predictive value, and positive predictive value of 0.8266, 0.8668, 0.8969, and 0.7841, respectively. The rate of inadequate specimens was 0.1280. For LBP, the DOR was 25.3587, with an AUC of 0.865. The sensitivity, specificity, negative predictive value, and positive predictive value were 0.8190, 0.8833, 0.8515, and 0.8562. The rate of inadequate specimens was 0.1729. For CS plus LBP, the AUC was 0.813, with a lower DOR of 9.4557 compared to individual methods. Diagnostic accuracy did not significantly differ among CS, LBP, and CS plus LBP. Subgroup analysis was used to compare ThinPrep and SurePath. The DORs were 29.1494 and 19.7734. SurePath had a significantly higher AUC.
CONCLUSIONS: There was no significant difference in diagnostic accuracy or proportion of inadequate smears between CS and LBP. SurePath demonstrated higher diagnostic accuracy than ThinPrep. Recommendations for fine-needle aspiration cytology should consider cost, feasibility, and accuracy.

OBJECTIVE: Molecular genetic testing in conjunction with cytopathology may improve prediction of malignancy in thyroid nodules, particularly those with indeterminate cytology (Bethesda III/IV). Though now commonplace in adults, pediatric data are limited. This study examines molecular genetics of pediatric nodules with correlation to cytologic and histologic classification at time of surgery and the distribution of mutations.
METHODS: Retrospective chart review of 164 patients <22 years who underwent surgical resection of a thyroid nodule between 2002 and 2020 with molecular testing on fine-needle aspiration biopsy (FNA) or final histopathology.
RESULTS: 85 (52 %) of 164 patients undergoing thyroid resection had available molecular genetic testing. BRAF V600E testing was performed on the FNA samples of 73 (86 %) patients and on 15 (18 %) surgical specimens; 31 (37 %) were positive. Of the remaining 54 patients, 21 had additional mutation/fusion testing. In 17 (81 %) cases, an alternate mutation/fusion was identified including 8 gene fusions, 3 DICER1 mutations, 4 NRAS mutations, one BRAF variant, and one unknown variant. BRAF, DICER1 mutations, and gene fusions predicted malignancy. Greater than 95 % of BRAF mutations were in Bethesda V/VI lesions and associated with classic variant PTC whereas fusions and DICER1 mutations clustered in Bethesda IV nodules. Bethesda III nodules harbored BRAF and NRAS mutations. In Bethesda IV nodules, a gene fusion or DICER mutation altered the surgical decision-making (upfront thyroidectomy rather than lobectomy) in 70 % of nodules submitted for genetic testing.
CONCLUSIONS: Expanded molecular genetic testing on FNA of pediatric thyroid nodules, particularly Bethesda III/IV, may improve prediction of malignancy and augment surgical decision-making.
METHODS: III.

OBJECTIVE: The utility of repeating ultrasound-guided fine-needle aspiration (US-FNAB) in the follow-up of benign (THY2) thyroid nodules is still debated. The aim of this study was to retrospectively investigate the diagnostic value of re-biopsy of thyroid nodules following an initially benign result.
METHODS: We retrospectively analyzed US-FNABs performed at the Unit of Endocrinology of Modena from 2006 to 2009. The firstly benign cytological result was compared with the cytological results of subsequent US-FNABs (2nd and/or 3rd) executed on the same nodule.
RESULTS: Among 10449 US-FNABs, 6270 (60%) received a THY2 cytological categorization. Of them, 278 (4.43%) underwent a subsequent US-FNAB: 86.7% maintained the same cytology, 32 (11.5%) changed to THY3 (indeterminate) and 5 (1.8%) to THY4 (suspicious of malignancy). Among the 24 nodules addressed to surgery, 9 (37%) were histologically malignant, with an overall miss rate of 3.2%. Male patients had higher risk of discordant results at subsequent US-FNAB (p = 0.005, OR:3.59, 95%CI:1.453-7.769) while dimensional increase above 5 mm was predictive of concordant benign cytology (p = 0.036, OR:0.249, 95%CI:0.068-0.915). Age, suspicious US characteristics, and distance between US-FNABs resulted not predictive.
CONCLUSIONS: Re-biopsy of benign nodules confirmed the benign nature in most cases. In case of discordant cytology, relocation in indeterminate category was the most common. The histological diagnosis of cancer occurred in one quarter of nodules surgically removed, with a low overall clinically significant miss rate. Thus, a small percentage of false negatives exists; males and subjects with US suspicious nodules should be carefully followed-up, considering case by case re-biopsy possibility.

OBJECTIVE: Interventional pathologists have expanded their expertise by acquiring proficiency in ultrasound-guided thyroid fine-needle aspiration biopsy (FNAB) and are now required to optimize punction procedures due to low resources and digital workflows. The aim of this study is to compare FNAB sample adequacy in two series with one versus two slides available for cytopathological analysis and its influence on diagnosis categorization, time taken to reach a final diagnosis, scanning time and size of the digital files produced.
METHODS: Patients were retrospectively selected based on the sampling of thyroid nodules using either two glass slides (two-slide group) or one slide only (one-slide group) and cytological diagnosis was performed using the second edition of the Bethesda system. For each group, the initial 15 cases were sorted to be scanned.
RESULTS: From a total of 713 procedures, 328 were sampled into two slides and 385 on one slide only. No significant differences were found regarding nodule size, location or EU-TIRADS classification between the two groups. The one-slide group did not exhibit a higher prevalence of non-diagnostic or atypia of undetermined significance (AUS) categories. As expected, the mean time taken to finalize diagnoses in cases where only one slide was prepared was 1.2 days faster. Scanning time and total file size were also significantly smaller in the one-slide group.
CONCLUSIONS: Adopting the \'one nodule-one puncture-one slide\' strategy for thyroid FNAB optimization enhances procedural efficiency in digital workflows, leading to cost savings without compromising diagnostic accuracy.

Background: Risk stratification systems for thyroid nodules are limited by low specificity. The fine-needle aspiration (FNA) biopsy size thresholds and stratification criteria are based on evidence from the literature and expert consensus. Our aims were to investigate the optimal FNA biopsy size thresholds in the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) and artificial intelligence (AI) TI-RADS and to revise the stratification criteria in AI TI-RADS. Methods: A total of 2596 thyroid nodules (in 2511 patients) on ultrasound examination with definite pathological diagnoses were retrospectively identified from January 2017 to September 2021 in 6 participating Chinese hospitals. The modified criteria for ACR TI-RADS were as follows: (1) no FNA for TR3; (2) FNA threshold for TR4 increased to 2.5 cm. The modified criteria for AI TI-RADS were as follows: (1) 6-point nodules upgraded to TR5; (2) no FNA for TR3; (3) FNA threshold for TR4 increased to 2.5 cm. The diagnostic performance and the unnecessary FNA rate (UFR) of modified versions were compared with the original ACR TI-RADS. Results: Compared with the original ACR TI-RADS, the modified ACR (mACR) TI-RADS yielded higher specificity (73% vs. 46%), accuracy (74% vs. 51%), area under the receiver operating characteristic curve (AUC; 0.80 vs. 0.70), and lower UFR (25% vs. 48%; all p < 0.001), although the sensitivity was slightly decreased (87% vs. 93%, p = 0.057). Compared with the original ACR TI-RADS, the modified AI (mAI) TI-RADS yielded higher specificity (73% vs. 46%), accuracy (75% vs. 51%), AUC (0.81 vs. 0.70), and lower UFR (24% vs. 48%; all p < 0.001), although the sensitivity tended to be slightly decreased (89% vs. 93%, p = 0.13). There was no significant difference between the mACR TI-RADS and mAI TI-RADS in the diagnostic performance and UFR (all p > 0.05). Conclusions: The revised FNA thresholds and the stratification criteria of the mACR TI-RADS and mAI TI-RADS may be associated with improvements in specificity and accuracy, without significantly sacrificing sensitivity for malignancy detection.