Diagnostic Cytopathology

INTRODUCTION: Insulinoma-associated protein 1 (INSM1) is a newly characterized sensitive and specific immunohistochemical marker for neuroendocrine (NE) tumors. Whereas more traditional NE markers, such as chromogranin A and synaptophysin, are cytoplasmic, INSM1 is uniquely nuclear and thus could serve as a useful addition to NE tumor workup. While application of immunohistochemical studies to cytology specimens is becoming increasingly relevant, knowledge of the effects of the certain fixatives as well as the pattern and intensity of immunoexpression are important considerations...

NUT carcinoma (NC) is a highly aggressive, poorly differentiated carcinoma that harbors a t(15:19) translocation, leading to the fusion of the NUTM1 gene. While the upper aerodigestive tract along the midline (head, neck, thorax, and mediastinum) is commonly reported as the primary site of NC, subsequent cases have emerged in diverse locations. Achieving a definitive diagnosis based solely on morphology is challenging; however, it can be achieved using immunohistochemistry (IHC) specific to the NUT antibody or by demonstrating the characteristic BRD4::NUTM1 fusion...

Human papillomavirus (HPV) is the most common sexually transmitted pathogen that causes anogenital disease. Cervical screening by cytology and HPV testing (co-testing) are important in prevention of cervical cancer. The Bethesda System category of atypical squamous cells (ASC) is used when a neoplastic process cannot be confidently identified. In such cases, the differential diagnosis is broad and includes benign conditions. Monitoring of ASC/SIL ratio is a commonly used laboratory quality assurance measure to prevent over- or under-use of this category...

We present a case report of a 76-year-old male with a histologically confirmed KRAS mutated, thyroid transcription factor 1 (TTF1) positive, grade 1, mucinous adenocarcinoma with cytologically difficult to interpret lymph node metastasis showing loss of TTF1 expression and overlapping features with goblet cell hyperplasia. The case highlights the importance of molecular testing in aiding diagnosis and guiding treatment of non-small cell lung carcinomas (NSCLC).

A cytopathology fellowship match would create an enforced and structured recruitment timeline for the benefit of applicants and programs. Major benefits would include delaying fellowship applications to allow residents to explore different subspecialty areas, a standardized application process for administrative ease, and optimization of matches between applicants and programs based on ranked preferences rather than use of time-limited "exploding offers." The overall gains in efficiency and achieving the primary goals of supporting trainees and recruiting in an equitable and inclusive manner outweigh any downsides to instituting a cytopathology fellowship match...

In the 21st century, there has been a dramatic shift in the diagnosis and management of non-small cell lung carcinoma (NSCLC), with an increasing use of minimally invasive tissue acquisition methods. Current treatments require morphologic subtyping and biomarker information in all cases. Determining such biomarkers is a continuously evolving field; current guidelines state that the determination of mutations on the Epidermal Growth Factor (EFGR), Kirsten Rat Sarcoma viral oncogene homolog (KRAS), Proto-oncogene B-Raf (BRAF), Human epidermal growth factor receptor 2 (HER2) and Anaplastic Lymphoma Kinase (ALK), genes as well as fusions on genes such as ROS Proto-Oncogene 1, Receptor Tyrosine Kinase (ROS1), MET proto-oncogene, receptor tyrosine kinase (MET), RET proto-oncogene (RET), and the Neurotrophic Tyrosine Receptor Kinase (NTRK) family is mandatory...

Isolated pulmonary cysticercosis is a rare manifestation of human cysticercosis which mainly affects central nervous system, skeletal muscles, eyes and subcutaneous tissues. Pulmonary involvement is usually a part of disseminated disease and mainly presents as bilateral pulmonary nodules. We report a rare case of isolated pulmonary cysticercosis presenting as lung cyst with pleural effusion. The diagnosis was made on pleural fluid cytology and cell block preparation. Herein we wish to recapitulate the importance of cell block as a diagnostic aid for parasitic infections, where morphological features and architectural patterns are as clearly discernable as in histopathology...

Isolated intraparotid neurofibromas are exceptionally rare and often associated with neurofibromatosis type 1 (NF1). Diagnosing these tumors proves challenging because of the clinical resemblance to primary salivary gland masses. This case report details an 18-year-old with a painful, enlarging parotid mass, diagnosed through fine needle aspiration biopsy (FNAB) revealing myxoid stroma and spindle cells. Magnetic resonance imaging confirmed a plexiform neurofibroma involving the parotid gland and facial nerve...

BACKGROUND: Fine needle aspiration cytology (FNAC) is the most useful tool in the diagnosis of thyroid nodules. Liquid-based cytology (LBC) is replacing the conventional smear (CS) for evaluation of thyroid FNAC. In our institution, thyroid FNAC preparation was changed from CS to LBC SurePath in July 2016. This study aimed to compare the diagnostic value of SurePath with that of CS in thyroid lesions. METHODS: A total of 35,406 samples of thyroid FNAC (11,438 CS and 23,968 SurePath), collected from January 2010 to December 2022, were included in this study...

This report describes the cytologic features of a recently described MXD4::NUTM1-rearranged colonic sarcoma metastatic to the midclavicular soft tissue. Thirteen years ago, a 65-year-old woman presented with a cecal mass and subsequent liver mass. The cecal mass was diagnosed as malignant undifferentiated spindled and epithelioid neoplasm based on morphology and lack of tumor immunoreactivity with a panel of epithelial, smooth muscle, skeletal, melanoma, hematologic, and GIST markers. The liver mass showed morphologic and immunophenotypic similarity to the epithelioid component of the patient's cecal mass, albeit devoid of the spindled component...

Ewing sarcoma (ES) usually arises from long bones and affects the head and neck region in only 1%-4% of cases. We reported clinical, radiographic, cytomorphologic, and histomorphologic findings of the ES in the mandible, because of its rarity and radiologically misinterpreted as a parotid gland tumor. A 26-year-old male patient presented with a history of painfull cheek swelling. On magnetic resonance imaging, a mass measuring 50 × 48 × 45 mm was found eroding mandible and pushing back the parotid gland...

Oncocytic lesions of the thyroid are a heterogeneous group encompassing nonneoplastic and neoplastic entities ranging from benign to malignant and have traditionally been classified as separate entities in thyroid pathology. To illustrate the diversity of these thyroid lesions, we describe three cases of fine needle aspiration biopsies (FNAB) diagnosed as Bethesda Category IV: Follicular neoplasm, oncocytic type, under the 2017 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), with ThyroSeq v3 molecular testing and subsequent surgical excision...

No abstract text is available yet for this article.

Fine needle aspiration biopsy (FNAB) in low- and middle-income countries (LMIC), can provide minimally invasive, cost-effective tissue diagnosis with rapid assessment and specimen triage, which is advantageous in these resource-limited settings. Nevertheless, challenges such as equipment shortages, reagents, and lack of trained personnel exist. This article discusses the effectiveness of FNAB for diagnosis of malignant and inflammatory conditions across various organs, such as lymph nodes, breast, soft tissue, and thyroid and advocates for increased training opportunities and collaboration with academic centers to enhance diagnostic accuracy and access to pathology services...

No abstract text is available yet for this article.

BACKGROUND: Preferentially expressed antigen in melanoma (PRAME) has been introduced as a new melanoma marker and potential target for immunotherapy. While PRAME immunohistochemistry (IHC) is well documented in surgical pathology, similar data in cytology are limited. Metastatic melanoma is frequently diagnosed via cytology samples in which IHC plays an important role. We aimed to accordingly evaluate the performance of PRAME IHC in diagnosing metastatic melanoma in cytology samples relative to other commonly used melanoma markers...

BACKGROUND: Molecular triage of indeterminate thyroid aspirates offers the opportunity to stratify the risk of malignancy (ROM) more accurately. Here we examine our experience with ThyroSeq v3 testing. METHODS: We analyzed 276 of 658 (42%) fine needle aspiration samples classified as indeterminate thyroid nodules using ThyroSeq v3 (Sept 2017-Dec 2019). The test provides a ROM and detects specific mutations. Surgical diagnoses were reviewed. RESULTS: Of 276 ThyroSeq-tested cases, 42% (n = 116) harbored genetic alterations, whereas 64% (n = 74) had surgical follow-up...

No abstract text is available yet for this article.

Sebaceous carcinoma of the breast is an extremely rare histological subtype of breast cancer, with fewer than 30 cases reported to date. Because of its extremely rare histological presentation, there are few case reports that highlight its cytological findings. In this case report, the cytomorphological features of a sebaceous carcinoma of the breast are described in detail. Cytomorphological analysis revealed atypical cells presenting predominantly as loose clusters. No tubular or papillary structures were evident in the clusters and no mucin production was observed...

Epstein-Barr virus-positive mucocutaneous ulcer (EBVMCU) is a newly established immunodeficiency-related disease. Herein, we report a case of EBVMCU and focus on its cytological usefulness for diagnosis. An 82-year-old man manifested pharyngalgia, dysphagia, and oral pain. His medical history included rheumatoid arthritis that had been treated with methotrexate. Clinically, peritonsillar abscess was suspected, but since neoplastic lesions, including malignant lymphoma (ML), could not be excluded, a series of cytohistological examination was attempted...