Fine Needle Aspiration Research Articles

Fine-needle aspiration cytology of palisading adenocarcinoma: The first cytology report of a newly described salivary gland neoplasm.

Here, we report the first cytology findings of the newly characterized entity, palisading adenocarcinoma of the salivary gland, diagnosed in the sublingual gland of a 61-year-old female. The liquid-based cytology showed a moderately cellular aspirate containing three-dimensional clusters and trabeculae of tumor cells of various sizes. The cells had dark ovoid nuclei, finely granular chromatin, inconspicuous to punctate nucleoli, and ample cyanophilic cytoplasm with indistinct cell borders. In conventional smears, the cells displayed frequent crush artifacts and anisonucleosis resembling endocrine-type atypia. The background was clean, devoid of secretions, and contained singly dispersed tumor cells with stripped nuclei. Interestingly, concentrically laminated globules of extracellular matrix surrounded by the tumor cells were identified. Mitotic figures and tumor necrotic debris were absent. The cytologic findings correlated with the histologic findings of the excision specimen. The cytologic differential diagnosis and tumor grading of palisading adenocarcinoma were briefly discussed.

The Combined Use of Fine-Needle Aspiration (FNA) and BRAF V600E Gene Testing: Can it Increase the Definitive Diagnosis Rate of Nodules Categorized as Bethesda III for Papillary Thyroid Carcinoma?

This study aimed to analyze the malignant probability of thyroid nodules diagnosed as indeterminate cytology, including atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS), and investigate the diagnostic value of combining BRAF V600E gene testing within this classification. We conducted a retrospective analysis of 126 patients who underwent fine-needle aspiration (FNA) examination of thyroid nodules and subsequent surgical treatment at Beijing Haidian Hospital between October 2021 and November 2022. Among them, there were 22 male and 104 female patients, aged between 18 and 75years old. Surgical pathology results were considered the gold standard for diagnosing the nature of thyroid nodules, evaluating the malignant incidence of cytological results categorized as AUS/FLUS. Fisher's exact test and diagnostic test evaluation methods were used to analyze the discriminatory diagnostic efficacy of preoperative FNA combined with BRAF V600E gene testing for papillary thyroid carcinoma (PTC). Statistical analysis was performed using SPSS 22.0 software. In PTC patients, the BRAF V600E gene mutation rate was 87.93% (102/116). Within the category of FNA results as AUS/FLUS, the proportion of PTC was 60.00% (15/25). The specificity, sensitivity, positive predictive value, and negative predictive value of the BRAF V600E gene mutation in diagnosing PTC within the AUS/FLUS category were 10/10, 6/15, 6/6, and 10/19, respectively. The BRAF V600E gene mutation significantly increased the detection rate of PTC in patients classified under this cytology (P = 0.028, <0.05). Preoperative FNA combined with BRAF V600E gene mutation testing significantly enhances the malignant detection rate of thyroid nodules diagnosed cytologically as AUS/FLUS. This combined approach provides a potent tool to improve diagnostic accuracy in this indeterminate classification.

Prognostic Utility of the Flow Cytometry and Clonality Analysis Results for Feline Lymphomas.

Feline lymphoma, a prevalent cancer in cats, exhibits varied prognoses influenced by anatomical site and cellular characteristics. In this study, we investigated the utility of flow cytometry and clonality analysis via PCR for antigen receptor rearrangement (PARR) with respect to characterizing the disease and predicting prognosis. For this purpose, we received fine needle aspirates and/or blood from 438 feline patients, which were subjected to flow cytometry analysis and PARR. We used a subset of the results from patients with confirmed B- or T-cell lymphomas for comparison to cytological or histological evaluation (n = 53). Using them as a training set, we identified the optimal set of flow cytometry parameters, namely forward scatter thresholds, for cell size categorization by correlating with cytology-defined sizes. Concordance with cytological sizing among this training set was 82%. Furthermore, 90% concordance was observed when the proposed cell sizing was tested on an independent test set (n = 24), underscoring the reliability of the proposed approach. Additionally, lymphoma subtypes defined by flow cytometry and PARR demonstrated significant survival differences, validating the prognostic utility of these methods. The proposed methodology achieves high concordance with cytological evaluations and provides an additional tool for the characterization and management of feline lymphoproliferative diseases.

Endoscopic Ultrasound-Guided Through-the-Needle Biopsy: A Narrative Review of the Technique and Its Emerging Role in Pancreatic Cyst Diagnosis.

Pancreatic cystic lesions (PCLs) pose a diagnostic challenge due to their increasing incidence and the limitations of cross-sectional imaging and endoscopic-ultrasound-guided fine-needle aspiration (EUS-FNA). EUS-guided through the needle biopsy (EUS-TTNB) has emerged as a promising tool for improving the accuracy of cyst type determination and neoplastic risk stratification. EUS-TTNB demonstrates superior diagnostic performance over EUS-FNA, providing critical preoperative information that can significantly influence patient management and reduce unnecessary surgeries. However, the procedure has risks, with an overall adverse event rate of approximately 9%. Preventive measures and further prospective studies are essential to optimize its safety and efficacy. This review highlights the potential of EUS-TTNB to enhance the diagnostic and management approaches for patients with PCLs. It examines the current state of EUS-TTNB, including available devices, indications, procedural techniques, specimen handling, diagnostic yield, clinical impact, and associated adverse events.

Endoscopic ultrasound-guided bite-on-bite biopsy and endoscopic ultrasound-guided fine-needle aspiration in the diagnosis of gastric tumors with negative malignant endoscopy biopsies: a retrospective cohort study

Background Specific types of gastric tumors, including gastric linitis plastica and lymphoma, may cause extensive deep-layer infiltration, impeding an accurate diagnosis with endoscopic biopsy. This study aims to evaluate the efficacy of endoscopic ultrasound (EUS)-guided bite-on-bite biopsy and EUS-guided fine-needle aspiration (EUS-FNA) in diagnosing gastric malignancies with negative endoscopic biopsies. Methods We retrospectively analyzed suspicious malignant gastric lesion cases in our hospital from October 2017 to August 2023. Clinical manifestations, radiographical examinations, endoscopic examinations, histopathological results, and therapeutic strategies were recorded and analyzed. Results Forty malignant gastric tumor cases with negative endoscopic biopsies were incorporated into our study. EUS-guided bite-on-bite biopsy was performed in 16 cases exclusively, whereas 17 patients received EUS-FNA exclusively, and seven patients underwent both simultaneously. Among the 23 patients who received the EUS-guided bite-on-bite biopsy, 22 (95.7%) were diagnosed with malignancies. Among the 24 patients who received EUS-FNA, a total of 19 cases with malignancies (79.2%) were confirmed by EUS-FNA (p = 0.11): 13 gastric adenocarcinomas, five metastatic malignancies, and one malignant stromal tumor. No adverse events were observed in any of the cases. Conclusions EUS-guided bite-on-bite biopsy and EUS-FNA possess their advantages and disadvantages. EUS-guided bite-on-bite biopsy could serve as a reliable diagnostic method for shallow lesions with negative malignant endoscopic biopsies.

Clinical and Pathological Findings of Ulcerative Prepuce Squamous Cell Carcinoma in a Marwari Horse

Squamous cell carcinoma is one of the muco-cutaneous soft tissue growths occurs in horses. Proliferative external genitalia squamous growth is a common type. This case report is about ulcerative squamous growth which is common in eyeball but uncommon in prepuce area. A Marwari 11 year old stallion was presented to the Veterinary Clinical Complex, Veterinary College and Research Institute, Namakkal with the history of mass in the external genitalia which had increased in size gradually over 12 months with ulceration shown in the last 5 weeks of that period. On clinical examination, ulcerated mass was noticed in the prepuce. Pudental nerve block was done for physical examination. Fine needle aspiration cytology and impression smear didn’t reveal tumour pathology. The presented case was tentatively diagnosed as preputial tumour and planned to perform surgical excision. Under xylazine and ketamine anaesthesia and triple drip maintenance, the preputial tumour mass was excised and samples were sent for histopathology which revealed poorly differentiated squamous cell carcinoma. Post-operative antibiotics, painkillers were administered and wound dressing done for 5 days. Animal had an uneventful recovery without recurrence.

Severe Bilateral Sialadenitis of the Mandibular and Parotid Salivary Glands with Severe Panniculitis in a 2-Year-old Standard Poodle.

A 2-year-old male neutered Standard Poodle weighing 17.9 kg was presented to their primary care veterinarian for enlarged bilateral submandibular swellings following an interdog altercation sustained in the previous weeks. Cytology performed following fine-needle aspirates of the regions of swelling was inconclusive, and the patient was treated empirically with Clavaseptin. Despite treatment, the submandibular swellings continued to enlarge, and right-sided intermittent epistaxis was reported. On biochemical profile, there was mild hypercalcemia and mild hyperglobulinemia. The computed tomography (CT) findings were indicative of severe multifocal sialadenitis with severe regional cellulitis and inflammatory lymphadenopathy. Histopathology and cytology results described mixed inflammation of the salivary gland. Methenamine silver staining and Fite's acid-fast staining were negative. Aerobic and anaerobic cultures were negative. Targeted, next-generation DNA sequencing detected no known fungi or bacterial pathogens. These findings were consistent with the diagnosis of severe bilateral mandibular sialadenitis, panniculitis, and lymphadenopathy. The patient was prescribed enrofloxacin, clindamycin, phenobarbital, and prednisolone for 1 month. One week after initiating treatment, the patient had a significant reduction in size of the salivary glands. CT imaging was helpful in the diagnosis of this patient and allowed the clinician to identify which submandibular anatomical structures were abnormal, guiding subsequent diagnostic decisions to provide medical management to resolve the condition.

Assessment of Ki-67 Proliferative Index in Cytological Samples of Nodal B-Cell Lymphomas.

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. 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. 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. The Ki-67 PI, assessed by manual counting and eyeballing in cytological samples, accurately differentiates between indolent and aggressive nBCLs.

"Immunocytochemistry in Cytology: Myth or Reality": Unraveling the Myth - Immunocytochemistry Applications in Thyroid Lesions.

Fine-needle aspiration cytology serves as an important preoperative diagnostic tool for thyroid nodules. Despite its excellent diagnostic accuracy, diagnoses based solely on morphological observation can be challenging. Therefore, various ancillary diagnostic techniques have been applied, including immunocytochemistry (ICC). This review discusses the application and evaluation of ICC in thyroid fine needle aspiration. Currently, three immunostaining preparation methods are available for cytological materials: liquid-based cytology, cell block, and cell transfer. ICC proves valuable in scenarios such as tumour diagnosis, assessment of differentiation and grading of carcinomas, estimation of primary organs in metastatic carcinomas, and detection of gene abnormalities. However, ICC, while useful, is not as accurate as immunohistochemistry and is more difficult to evaluate. If the pitfalls and limitations are understood and effectively navigated, ICC could play a significant role in decreasing the non-diagnostic rate, thus leading to more accurate and valuable diagnoses and reductions in the re-aspiration rate.

Revisiting Pulmonary Sclerosing Pneumocytoma.

Pulmonary sclerosing pneumocytoma (PSP) is a quite rare tumor outside Eastern countries. This rarity, together with a wide histological appearance, makes its correct identification a diagnostic challenge for pathologists under the microscope. Historically, PSP was considered a vascular-derived neoplasm (sclerosing hemangioma), but its immunohistochemical profile clearly supports its epithelial origin. No specific molecular fingerprint has been detected so far. This short narrative revisits the clinical, histological, immunohistochemical, and molecular aspects of this tumor, paying special attention to some controversial points still not well clarified, i.e., clinical aggressiveness and metastatic spread, multifocality, the supposed development of sarcomatoid change in a subset of cases, and tumor associations with lung adenocarcinoma and/or well-differentiated neuroendocrine hyperplasia/tumors. The specific diagnostic difficulties on fine-needle aspiration cytology/biopsy and perioperative frozen sections are also highlighted. Finally, a teaching case of tumor concurrence of lung adenocarcinoma, neuroendocrine lesions, and PSP, paradigmatic of tumor association in this context, is also presented.

Non-Surgical Treatment of Residual Cyst in Maxillary Anterior Region of an 11-year-old Patient: A Case Report

We aim to report a case of residual cyst in an 11-year-old male patient, which was treated by marsupialization as a conservative alternative to surgical enucleation. An 11-year-old male patient reported to our department with a painless swelling of approximately 1.5x1 cm in size intraorally, both in the maxillary right buccal and palatal region for about 1 month. On fine needle aspiration, a yellow-coloured highly viscous fluid was observed which on histopathological examination revealed an infected cyst. This along with the clinical examination and history confirmed the diagnosis of a residual cyst. Marsupialization was chosen as a conservative treatment due to the size of the cyst and the age of the patient. Weekly follow-up and dressing change were carried out for 6 months which lead to a complete resolution of the cyst with continuous normal development of the occlusion. No adverse effects such as fever, infection, or pus discharge were seen at any time during treatment. We have been able to design a treatment protocol which has provided us with a nonsurgical solution for large cystic lesions in growing patients without adverse effects for the complete duration of treatment. Marsupialization should be considered as a treatment option for large residual cysts, especially in pediatric patients. Key Words - Marsupialization, Maxilla, Mixed dentition, Residual cyst

Current status of endoscopic ultrasound in the diagnosis of intraductal papillary mucinous neoplasms.

The new Kyoto guidelines for the management of intraductal papillary mucinous neoplasm (IPMN) provide evidence-based recommendations for the diagnosis and treatment of IPMN. Endoscopic ultrasonography (EUS) is a diagnostic modality with a high spatial resolution that allows detailed observation and obtaining cyst fluid or tissue samples via EUS-guided fine needle aspiration (EUS-FNA). Currently, EUS is an indispensable examination method for the diagnosis of pancreatic diseases. On the other hand, there have been concerns that EUS imaging tends to be highly operator-dependent, and may lack objectivity. Previous guidelines have assigned EUS as an option for patients with worrisome features. However, recent reports indicate that the sensitivity of EUS for the diagnosis of mural nodules (MNs) is more than 90%, comparable or superior to that of contrast-enhanced computed tomography or magnetic resonance cholangiopancreatography. The specific advantages of EUS in the diagnosis of IPMN are: (1) high spatial resolution imaging for the diagnosis of MNs, (2) contrast-enhanced EUS for differentiation of intra-cystic MNs from mucous clots, and (3) pathological diagnosis using EUS-FNA and differential diagnosis of a pancreatic cystic tumor by cystic fluid analysis. In order to utilize EUS in the diagnosis of IPMN, endoscopists are required to have the skills to provide sufficiently objective imaging findings.

Oncological Outcome and Treatment Options of Medullary Thyroid Cancers: Experience at a Tertiary Cancer Centre

Introduction: Medullary thyroid carcinoma (MTC) is a rare type of thyroid cancer and the main treatment is surgery. The extent of surgery depends on the spread of tumour and often involves thyroidectomy and neck dissection. Recurrent or metastasis tumour can be detected with raising calcitoninand there are various options of treatment. Methods: This was a retrospective study of MTC over seven years in a tertiary cancer centre which evaluated the treatment outcome and the non-surgical options available in recurrent and metastatic tumours. Results: Among the 601 thyroid cancers, 34 patients (5.3%) were MTC, of which 29 were studied. Majority were women, below 60 years, were diagnosed with fine needle aspiration cytology of thyroid nodule or nodes and had raised calcitonin value (Ctn). The value of Ctn was correlated with tumour burden rather than extent (p=0.7). Recurrence was seen in 35% and all patients with locoregional recurrence had curative surgery whereas metastatic patients were offered palliative treatment. Acceptance of palliative treatment was less due to financial burden. The five year overall survival for nonmetastatic disease was 89.4 % and for patients with metastatic disease at presentation was 54.7 %. Conclusion: The incidence of medullary thyroid carcinoma is low compared to the differentiated thyroid carcinoma. The main treatment is surgery and other treatment options are limited.

Role of Elastography in Differentiating Malignant and Benign Thyroid Nodules using FNAC as a Reference Standard

Objective: To determine the efficacy of elastography in differentiating between malignant and benign thyroid nodules, using fine needle aspiration cytology (FNAC) as the reference standard. Methodology: This cross-sectional study was conducted at the Radiology Department of Nishtar Hospital, Multan, from January 2023 to December 2023. A total of 180 patients with one or more solid thyroid nodules diagnosed on conventional ultrasound were enrolled in the study. After obtaining consent, all patients underwent strain elastography under standard protocol, and the findings were compared with cytological results. Sensitivity was calculated using the formula: True Positives / (True Positives + False Negatives). Specificity was calculated as: True Negatives / (True Negatives + False Positives). Positive predictive value (PPV) was calculated as: True Positives / (True Positives + False Positives). Negative predictive value (NPV) was calculated as: True Negatives / (True Negatives + False Negatives). Diagnostic accuracy was determined using the formula: (True Positives + True Negatives) / (True Positives + True Negatives + False Positives + False Negatives). All these values were calculated using a 2x2 contingency table. Results: The study included a total of 180 patients with an average age of 46.38±12.21 years, 76.1% of whom were male and 23.9% female. Among the patients, 9.4% had malignant thyroid nodules, while 90.6% had benign nodules as determined by elastography and confirmed by FNAC. In terms of diagnostic accuracy, 13 patients were true positives (both positive on cytology FNAC and ultrasound elastography), whereas 7 patients were false positives (negative on cytology FNAC but positive on ultrasound elastography). Conclusion: Elastography has high efficacy in differentiating malignant from benign thyroid nodules and can potentially replace fine needle aspiration cytology (FNAC).

A Neglected Tropical Disease: Thoracic Actinomycetoma a Succesfull Case Report

Mycetoma is a chronic, granulomatous subcutaneous infection characterized by a triad of inflammation, painless tumour-like lesions and multiple sinuses discharging grains [1]. In Mexico, 97% of mycetomas are caused by bacteria of the order Actinomycetales, where Nocardia brasiliensis is the most important agent, while in eumycetomas the most important genera are Madurella spp. and Trematosphaeria spp [4]. This pathology is more common in men (3:1 to 5:1) between the age of 20 and 40 years, and up to 75% of patients present the injury (being the entry way) in the lower extremity, most commonly in the foot (70%). Other sites include the head, neck, chest, shoulders and arms [6, 7]. The diagnosis of mycetoma is based on clinical presentation, imaging studies and identification of the causative organisms in relevant clinical samples taken from affected tissues using fine-needle aspiration, or surgical biopsy. The diagnosis of mycetoma is based on clinical presentation, imaging studies and identification of the causative organisms in relevant clinical samples taken from affected tissues using fine-needle aspiration, or surgical biopsy. Imaging including X-ray, ultrasound, MRI and CT scan examinations may be required to characterize the spread and extent of disease [3].

Lymphadenopathy Tissue Sampling by EUS-Guided Fine-Needle Biopsy Contributes to Meeting the Conditions for Genomic Profiling.

EUS-guided fine-needle biopsy (EUS-FNB) performed with a Franseen needle or Fork-tip needle enables greater tissue acquisition. However, it is unknown whether EUS-FNB could contribute to lymphadenopathy genomic profiling. The aim of this study was to determine the efficacy of EUS-FNB using a Franseen or Fork-tip needle for tissue acquisition and genomic profiling in patients with lymphadenopathy. Patients with abdominal lymphadenopathy who underwent EUS-guided fine needle aspiration (FNA)/EUS-FNB were included in this study. The amount of acquired tissue and its suitability for genomic profiling were compared between FNA and FNB. Specimen quality was evaluated by a widely used pathologic adequacy scoring system (0: insufficient; 1 to 2: cytologic; 3: limited histologic; 4 to 5: sufficient histologic). The criteria of FoundationOne CDx (F1CDx) and NCC Oncopanel (NOP) were used to assess the suitability for genomic profiling. In total, 72 patients underwent EUS-FNA, and the other 20 patients underwent EUS-FNB. The pathologic adequacy score and suitability for genomic profiling based on the criteria were significantly higher for FNB than for FNA [histologic adequacy score: 5 (4 to 5) versus 3 (0 to 5), P<0.01; F1CDx: 16.7% vs. 0%, P=0.01; NOP: 66.7% vs. 7.5%, P<0.01]. In multivariate analysis, EUS-FNB was identified as the only factor that influenced the suitability for genomic profiling based on the above-mentioned criteria (odds ratio 19.5, 95% CI: 3.74-102, P<0.01). EUS-FNB performed using Franseen or Fork-tip needles may result in greater lymphadenopathy tissue acquisition and thus enhanced suitability for genomic profiling compared with EUS-FNA.

Myxoid liposarcoma diagnosed on fine needle aspiration cytology: There is more to it than meets the eye.

Liposarcoma is a rare mesenchymal neoplasm commonly involving deep soft tissues and the retroperitoneum. Among the various types of liposarcoma, myxoid liposarcoma is the most frequently encountered in adolescents and young adults, with a predilection for lower extremities. Fine needle aspiration allows easy assessment and rapid on-site evaluation for distinguishing benign from malignant lipomatous lesions. Here, we present a case of myxoid liposarcoma in the calf region of a 19-year-old boy, diagnosed via fine needle aspiration cytology, and subsequently confirmed by histopathological examination after surgical resection. The intention behind this case report is to highlight the cytological features of myxoid liposarcoma and to improve understanding of this tumor entity, aiming to prevent misdiagnosis by inexperienced pathologists when evaluating cytology specimens.

Oncocytic/Hürthle cell lesions have the same implied risk of neoplasm/malignancy as their follicular counterparts.

There are conflicting results on whether the presence of oncocytes modifies the risk of neoplasm (RON) or malignancy (ROM) for thyroid fine-needle aspirates (FNAs): Atypia of undetermined significance AUS and Follicular Neoplasm, FN, or Oncocytic Neoplasm, ON. To our knowledge, the effect of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) has not yet been studied. We compared RON and ROM between follicular type AUS (AUS-FT) and oncocytic type AUS (AUS-OT) and between FN and ON. We retrospectively analysed all thyroid FNAs with the diagnostic category of AUS-other or Neoplasm (2005-2015). AUS-FT had predominance of microfollicles and AUS-OT had predominance of oncocytes. Histology follow-up was then reviewed and RON, ROM was then calculated and compared (significant at p < 0.05). We repeated the search for 2018 to evaluate for NIFTP effect. Pre-NIFTP, 859/5063 cases (17%) were AUS-FT, AUS-OT, FN, and ON. Histology follow-up was available for 297 cases (35%). RON was 83/183 (45%) for AUS-FT, 35/76 (46%) for AUS-OT, 15/25 (60%) for FN and 11/13 (85%) for ON. Post-NIFTP, RON was 11/31 (35%) for AUS-FT, 5/8 (63%) for AUS-OT, 1/2 (50%) for FN and 4/5 (80%) for ON. For both periods, RON, ROM of AUS-FT was not significantly different than AUS-OT, and no significant differences were observed comparing FN and ON. The predominance of oncocytes does not modify the implied RON, ROM for categories of AUS or FN\ON, even after the adoption of NIFTP.

Angiomyomatous hamartoma: Unusual presentation of a rare entity

Angiomyomatous hamartoma (AMH) is a rare benign vascular growth primarily affecting inguinal and femoral lymph nodes (LNs). Here, we present a unique case of AMH manifesting as a submental neck mass, a location seldom reported in literature. A 20-year-old male presented with a palpable midline neck mass adjacent to the hyoid bone. Ultrasonography suggested a partially cystic lesion, prompting consideration of thyroglossal duct cyst or necrotic lymph node. Fine-needle aspiration (FNA) hinted at a benign cystic lesion, potentially a thyroglossal duct cyst. Surgical excision via the Sistrunk approach revealed no cyst but characteristic features of AMH upon histopathological examination. This case underscores the importance of considering AMH in the differential diagnosis of subcutaneous nodules in unusual locations and highlights the role of surgical excision for both diagnosis and treatment. Our findings expand the understanding of AMH's clinical presentation and emphasize the necessity of a comprehensive differential diagnosis approach for nodal lesions.

Liquid-based cytology features of pancreatic acinar cell carcinoma: comparison with other non-ductal neoplasms of the pancreas.

Acinar cell carcinoma (ACC) is a rare malignant epithelial neoplasm, which shares many cytomorphological features with other non-ductal pancreatic neoplasms such as pancreatic neuroendocrine neoplasm (PanNEN) and solid-pseudopapillary neoplasm (SPN). Due to the relative rarity of these tumors, pathologists are less familiar with the cytological features, especially on liquid-based cytology (LBC) which has been relatively recently introduced for endoscopic ultrasound-guided fine needle aspiration specimens. We evaluated the detailed cytological features of 15 histologically confirmed ACC (7 conventional smears [CS], 8 LBC), and compared them with the LBC features of SPN (n = 9) and PanNEN (n = 9). Compared with CS, LBCs of ACC demonstrated significantly less bloody background. All ACCs demonstrated prominent nucleoli and macronucleoli on LBC. On comparison with the LBC features of SPN and PanNEN, most ACCs demonstrated a necrotic background with apoptotic debris while PanNEN and SPN did not show these features. Acinar structures were predominantly observed in ACC, while frequent pseudopapillary structures were seen only in SPN. Prominent nucleoli and macronucleoli were only seen in ACC. ACC had characteristic cytological features that could be observed on LBC preparations, such as high cellularity, necrotic/apoptotic background, nuclear tangles, acinar arrangement of cells, and macronucleoli. These findings also help distinguish ACC from PanNEN and SPN on LBC. It is important to be familiar with these features, as an accurate diagnosis on endoscopic ultrasound-guided fine needle aspiration cytology would have impact on the management of the patient.