Non-gastrointestinal stromal tumor, mesenchymal neoplasms of the gastrointestinal tract: a review of tumor genetics, pathology, and cross-sectional imaging findings.

There is a diverse group of non-gastrointestinal stromal tumor (GIST), mesenchymal neoplasms of the gastrointestinal (GI) tract that demonstrate characteristic pathology and histogenesis as well as variable imaging findings and biological behavior. Recent advancements in tumor genetics have unveiled specific abnormalities associated with certain tumors, influencing their molecular pathogenesis, biology, response to treatment, and prognosis. Notably, giant fibrovascular polyps of the esophagus, identified through MDM2 gene amplifications, are now classified as liposarcomas. Some tumors exhibit distinctive patterns of disease distribution. Glomus tumors and plexiform fibromyxomas exhibit a pronounced affinity for the gastric antrum. In contrast, smooth muscle tumors within the GI tract are predominantly found in the esophagus and colorectum, surpassing the incidence of GISTs in these locations. Surgical resection suffices for symptomatic benign tumors; multimodality treatment may be necessary for frank sarcomas. This article aims to elucidate the cross-sectional imaging findings associated with a wide spectrum of these tumors, providing insights that align with their histopathological features.

AIns (insulin) type amyloidoma of the extremity diagnosed by fine-needle aspiration.

Amyloid is an extracellular deposition of Congo red positive material which shows apple green birefringence under polarized light. A cytopathologist can uncommonly encounter such cases. Among the reported cases, a fine-needle aspiration (FNA) of amyloid is frequently misinterpreted as acellular nondiagnostic material. We report a case of amyloidoma of the right upper arm in a 68-year-old man with history of renal transplantation for diabetic nephropathy who presented with loss of appetite and weight loss. Physical exam showed a 7 cm hard nodular subcutaneous mass in the right upper arm. FNA yielded abundant acellular, irregular fragments of dense material, which was Congo red positive with apple green birefringence by polarized light, consistent with amyloid. Further subtyping of the amyloid by mass spectrometry, showed AIns (insulin)-type amyloid deposition. After further questioning, the patient admitted to injecting insulin at the same site for many years. Awareness of the cytological features is important for diagnosis. This is especially important when dealing with uncommon sites and without adequate clinical information.

Fine-needle aspiration of amyloidoma: A critical analysis.

BACKGROUND: Amyloid, presenting as a mass, is termed amyloidoma. Among the reported cases, fine-needle aspiration (FNA) of amyloid is often misinterpreted as acellular nondiagnostic material. METHODS: A computer search of all FNAs was performed and cases diagnosed as amyloidoma were identified. RESULTS: Among 11,956 cases and 20,634 FNAs, there were six cases and 12 FNAs of amyloidoma. One case with mucin/myxoid matrix was misinterpreted as amyloid, which on our review was Congo red negative. All five other cases of amyloidoma were adequate for evaluation. The smears showed most of the aspirated contents in the middle of the slide and it did not spread when smeared. The amyloid was present as large chunks of waxy, smooth, orangophilic/cyanophilic fragments on Papanicolaou stain and as basophilic fragments on Diff-Quik stain in a clean background. In cases with lymphoma/myeloma, there were admixed lymphocytes and/or plasma cells. Unlike fibrous tissue, amyloid aspirates well and provides adequate material for interpretation. The clean background distinguishes it from mucin/myxoid matrix. Congo red stain was positive with apple green birefringence in all five cases. Further subtyping by mass spectrometry showed AL (κ) type in three patients and AIns (insulin) type in one patient. In one patient with lymphoma, the subtyping was not done. CONCLUSION: FNA of amyloidoma is rare (0.04%), but an optimal method for diagnosis and subtyping, avoiding unwanted surgical interventions. Although mistaken for fibrous tissue, which aspirates poorly, abundant acellular orangophilic/cyanophilic material on FNA should raise a suspicion for amyloid. Unlike mucin/myxoid matrix, amyloid does not smear the background.

Small Bowel Neuroendocrine Neoplasms-A Review.

ABSTRACT: Neuroendocrine neoplasms (NENs) are rapidly evolving small bowel tumors, and the patients are asymptomatic at the initial stages. Metastases are commonly observed at the time of presentation and diagnosis. This review addresses the small bowel NEN (SB-NEN) and its molecular, histological, and imaging features, which aid diagnosis and therapy guidance. Somatic cell number alterations and epigenetic mutations are studied to be responsible for sporadic and familial SB-NEN. The review also describes the grading of SB-NEN in addition to rare histological findings such as mixed neuroendocrine-non-NENs. Anatomic and nuclear imaging with conventional computed tomography, magnetic resonance imaging, computed tomographic enterography, and positron emission tomography are adopted in clinical practice for diagnosing, staging, and follow-up of NEN. Along with the characteristic imaging features of SB-NEN, the therapeutic aspects of imaging, such as peptide receptor radionuclide therapy, are discussed in this review.

Tumefactive Nonneoplastic Proliferative Pseudotumors of the Kidneys and Urinary Tract: CT and MRI Findings with Histopathologic Correlation.

A diverse spectrum of pathologically distinct, nonneoplastic, proliferative conditions of the kidneys and urinary tract demonstrate a expansile growth pattern similar to that of neoplasms. The renal pseudotumors include myriad causes of infections as well as rare noninfectious causes such as sarcoidosis, amyloidosis, and immunoglobulin G4-related disease (IgG4-RD). Rare entities such as cystitis cystica, endometriosis, nephrogenic adenoma, and pseudosarcomatous myofibroblastic proliferation and distinct types of prostatitis comprise tumefactive nontumorous disorders that affect specific segments of the urinary tract. The pseudotumors of the kidneys and urinary tract demonstrate characteristic histopathologic and epidemiologic features, as well as protean clinical manifestations, natural history, and imaging findings. Many patients present with genitourinary tract-specific symptoms or systemic disease. Some cases may be incidentally discovered at imaging. Some entities such as perinephric myxoid pseudotumors, IgG4-RD, fibroepithelial polyp, and nephrogenic adenoma display specific anatomic localization and disease distribution. Imaging features of multisystem disorders such as tuberculosis, sarcoidosis, and IgG4-RD provide supportive evidence that may allow precise diagnosis. Fungal pyelonephritis, xanthogranulomatous pyelonephritis, IgG4-RD, actinomycosis, and endometriosis show markedly low signal intensity on T2-weighted MR images. Although some pseudotumors exhibit characteristic imaging findings that permit correct diagnosis, laboratory correlation and histopathologic confirmation are required for definitive characterization in most cases. A high index of suspicion is a prerequisite for diagnosis. Accurate diagnosis is critical for instituting optimal management while preventing use of inappropriate therapies or interventions. Surveillance CT and MRI are frequently used for monitoring the response of pseudotumors to therapy. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Mesotheliomas and Benign Mesothelial Tumors: Update on Pathologic and Imaging Findings.

A diverse spectrum of benign entities and malignant neoplasms originate from the monotonous mesothelium that lines the serosal membranes of the pleural, pericardial, and peritoneal cavities. The mesothelium of myriad sites shows a common origin from the lateral plate mesoderm; primary mesothelial tumors thus demonstrate similar pathogenesis, imaging findings, and treatment options. Significant changes have been made in the 2021 World Health Organization (WHO) classification schemata of the pleural and pericardial tumors on the basis of recent advances in pathology and genetics. While malignant mesotheliomas are biologically aggressive malignancies that occur primarily in patients exposed to asbestos with attendant poor survival rates, well-differentiated papillary mesothelial tumors and adenomatoid tumors charter a benign clinical course with an excellent prognosis. Mesothelioma in situ is a newly characterized entity represented by recurrent unexplained pleural effusions without any identifiable mass at imaging or thoracoscopy. Immunohistochemical markers based on BAP1, MTAP, CDKN2A, and TRAF7 gene mutations help differentiate diffuse mesotheliomas from benign mesothelial proliferations and localized mesotheliomas. Cross-sectional imaging modalities, including US, CT, MRI, and fluorine 18-fluorodeoxyglucose (FDG) PET/CT, permit diagnosis and play a major role in staging and assessing surgical resectability. Imaging studies are invaluable in providing noninvasive and quantitative assessment of tumor response in patients with unresectable disease. Owing to significant overlap in patient characteristics and pathomorphology, accurate diagnosis based on advanced histopathology techniques and genetic abnormalities is imperative for optimal management and prognostication. While patients with nonepithelioid pleural mesotheliomas benefit from immunotherapy, novel targeted therapies for CDKN2A-, NF2-, and BAP1-altered mesotheliomas are under consideration. © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Recurrent Neuroendocrine Primary Cutaneous Mucinous Carcinoma of the Scalp After Complete Excision.

ABSTRACT: Primary cutaneous mucinous carcinoma is a rare, indolent malignancy with a debated history regarding cell of origin. Recurrence is rare but has been documented in up to a third of cases. Recent literature reviews have recognized 2 possible subtypes-neuroendocrine and nonneuroendocrine- with different possible prognostic implications for patients. We describe a case of recurrent primary cutaneous mucinous carcinoma in a 50-year-old man with subtle neuroendocrine features not initially recognized on routine H&E staining but highlighted by immunohistochemical studies. We underscore the importance of immunohistochemical use in these rare cases and emphasize that awareness of these neuroendocrine and nonneuroendocrine subtypes is essential for a complete diagnosis.

Fine-needle aspiration of scalp masses: A review of 30 cases.

INTRODUCTION: Scalp masses are often the initial presentation of a widely disseminated malignancy. Fine-needle aspiration (FNA) is an optimal method for obtaining an accurate tissue diagnosis, in these patients with initial presentation and those with a known malignancy. MATERIALS AND METHODS: We reviewed all FNAs of skin and soft tissue lesions from the scalp at our institution over a period of 31 years (1990-2021). Relevant clinical information was obtained from the review of computerized patient record. The histologic type, presentation, previous diagnoses, and survival after the diagnosis were correlated. RESULTS: Thirty patients with scalp masses were identified. All the patients were males with a median age of 61 years (27-81 years). The scalp masses ranged from 0.4 to 6 cm in size. Ten cases (33%) were benign, but the majority of cases (n = 20, 67%) were malignant. Of the malignant lesions sampled, 1 case was a primary squamous-cell carcinoma (SCC), and the remaining 19 cases were metastatic tumors. Of these, 13 cases (68.4%) had a previously diagnosed malignancy. Most of the 19 metastatic lesions were adenocarcinomas or poorly differentiated carcinomas (n = 12, 63.2%), followed by melanoma (n = 4), SCC (n = 1), alveolar soft part sarcoma (n = 1) and large cell lymphoma (n = 1). The most common site of primary was the gastrointestinal tract (6/19, 31.5%) and lung (6/19, 31.5%). The average survival after the diagnosis of these scalp metastases was around 6.3 months, signifying a poor prognosis. CONCLUSION: In our patient population, most scalp masses were metastatic tumors. Metastasis to the scalp signals advanced disease and is associated with a very poor prognosis. FNA is an easy, safe, rapid, cost effective and precise modality for diagnosing these masses. It can also yield material for molecular testing for newer directed therapies, if needed.

Squamous cell carcinoma arising in an epidermal inclusion cyst.

Squamous cell carcinoma (SCC) arising from an epidermal inclusion cyst (EIC) is uncommon. We present a case of a 70-year-old man with a scalp nodule with persistent discharge that was resected based on the clinical impression of an EIC. Histopathologic exam showed an infundibular EIC with an epidermal type of squamous epithelium; however, some of the cyst lining and lumen was replaced by squamous proliferation with malignant features. There are 56 cases of SCC arising in EICs reported in the English literature. Though suspected EICs are commonly benign, a thorough pathologic evaluation is required to rule out malignancy.

Malignant Gastrointestinal Neuroectodermal Tumor: A New Kid on the Block?

ABSTRACT: Also referred to as "osteoclast-rich, clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT)," malignant gastrointestinal neuroectodermal tumor is a newly described, rare, aggressive sarcoma that commonly arises in the small bowel, stomach, and colon. Histogenesis is likely from an autonomous nervous system-related primitive cell of neural crest origin. The hallmark genetic finding of EWS-CREB1 or EWS-ATF1 fusion transcripts clinches the diagnosis. Annular constrictive lesions tend to be smaller, show homogenous contrast enhancement on computed tomography, and may present with bowel obstruction. Larger, expansile masses tend to be exophytic and show heterogeneous contrast enhancement. Surgical resection is the mainstay of treatment. Frequent recurrences, metastases, and death from disease in 75% of patients portend a poor prognosis. Targeted chemotherapy based on specific tumor pathways is being developed.

Mesenchymal neoplasms of the urinary bladder: a comprehensive review with focus on cross-sectional imaging findings.

Mesenchymal neoplasms of the urinary bladder are exceedingly rare and display remarkable diversity. These tumors demonstrate distinct pathological features as well as variable biological behavior and cross-sectional imaging findings. The rarity of tumors, nonspecific symptoms and seemingly normal cystoscopic findings (particularly with small and exophytic tumors) frequently lead to misdiagnosis or missed diagnosis. While some tumors display characteristic cross-sectional imaging findings that may suggest a diagnosis, imaging findings are mostly nonspecific. Histopathological examination is required for accurate diagnosis, management and prognostication. The purpose of this article is to review the cross-sectional imaging findings of a diverse spectrum of mesenchymal tumors of the urinary bladder.

Metastatic hepatocellular carcinoma to the bone diagnosed by fine needle aspiration in a veteran population.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and it may present initially with extrahepatic spread in 5%-15% cases. It most commonly metastasizes to lungs, lymph nodes and adrenal glands. Skeletal metastases from HCC are uncommon and carry a very poor prognosis. METHODS: We retrospectively reviewed all fine needle aspiration (FNA) specimens of metastatic HCC at our institution from January 1994 to March 2021 using the SNOMED search computer option. Relevant clinical information was obtained from the review of patient's electronic medical records. RESULTS: There were 36 FNAs of metastatic HCC over a period of 27 years. Six patients (16.7%) were found to have skeletal metastases. All six patients were males with a median age of 59 years (54-71 years) and their lesions were osteolytic. The most common site of metastases was vertebra (3/50%). Most patients (67%) had bone metastases as an initial presentation, without prior history of HCC. The mean survival after the diagnosis of skeletal metastases was only 8 months. CONCLUSION: Detection of extrahepatic HCC to bone is important to avoid any unwanted surgical intervention. In our patient population, the most common site of skeletal metastases from HCC was vertebra, therefore in FNAs of vertebral lytic masses, metastatic HCC should be considered. On FNA, extrahepatic metastases of HCC can mimic other poorly differentiated tumors. They behave in an aggressive fashion, resulting in a grim prognosis. Cytological substrates can be used for future molecular testing, if needed.

Mesenchymal Neoplasms of the Prostate and Seminal Vesicles: Spectrum of Disease with Radiologic-Pathologic Correlation.

There is a wide spectrum of benign and malignant mesenchymal neoplasms of the prostate, which account for less than 1% of all prostatic tumors. These include distinctive tumors that arise from the specialized prostatic stroma and site-agnostic neoplasms such as smooth muscle tumors, fibrous or myofibroblastic neoplasms, neurogenic tumors, vascular tumors, and a plethora of sarcomas. Select tumors show classic sites of origin within the prostate. While stromal tumors of uncertain malignant potential (STUMPs) commonly involve the peripheral zone at the prostate base, leiomyomas typically originate from the central prostate toward the apex. Some "prostatic" neoplasms such as gastrointestinal stromal tumors, solitary fibrous tumor (SFT), paragangliomas, and neurogenic tumors arise primarily from periprostatic soft tissues. Most mesenchymal tumors of the prostate and seminal vesicles manifest as large tumors that cause nonspecific symptoms; prostate-specific antigen level is not typically elevated. Diverse mesenchymal neoplasms demonstrate characteristic histopathologic and immunocytochemical features and variable cross-sectional imaging findings. While leiomyoma and SFT typically display low signal intensity on T2-weighted images, synovial sarcomas commonly show hemorrhage. Diagnosis is difficult because of the rarity and lack of awareness of the tumors and the significant overlap in histopathologic features. Select tumors show characteristic genetic abnormalities that allow the diagnosis to be established. For example, more than 90% of SFTs are characterized by a unique NAB2-STAT6 gene fusion, and more than 95% of synovial sarcomas are associated with a distinctive SYT-SSX chimeric transcript. Accurate diagnosis is imperative for optimal management owing to markedly different tumor biology as well as attendant therapeutic and prognostic implications. While STUMPs commonly recur, sarcomas typically charter an aggressive course with poor prognosis. Online supplemental material is available for this article. ©RSNA, 2022.

MET Gene High Copy Number (Amplification/Polysomy) Identified in Melanoma for Potential Targeted Therapy.

OBJECTIVES: Aberrant expression of the mesenchymal epithelial transition factor (MET) gene has been observed in several malignancies, and drugs targeting the MET gene have been implicated in clinical trials with promising results. Hence, MET is a potentially targetable oncogenic driver. We explored the frequency of MET gene high copy number in melanomas and carcinomas. METHODS: The study group included 135 patients. Tissue microarrays were constructed with 19 melanomas and 116 carcinomas diagnosed from 2010 to 2012. We screened MET gene copy number by fluorescence in situ hybridization analysis using probes for MET gene and CEP7 as control. RESULTS: We found MET gene amplification in 2 (11%) of 19 melanoma cases, whereas 5 (26%) of 19 melanoma cases showed polysomy. For carcinomas, there was no MET gene amplification identified. However, 8 (7%) of 116 cases showed polysomy. CONCLUSIONS: In our study, MET gene amplification was identified in 11% of melanomas and is relatively concordant with few reported studies. However, about 26% of the additional melanoma cases showed MET gene polysomy, which has not been reported as per our knowledge. If these results are validated with further orthogonal studies, more of the melanoma cases could potentially benefit from targeted therapy with MET tyrosine kinase inhibitors.

Clinical, Radiographic, Pathologic Characterization and Survival Outcomes of Nuclear Protein of the Testis Carcinoma.

INTRODUCTION: Nuclear protein of the testis (NUT) carcinoma (formerly NUT midline carcinoma) is an aggressive tumor with characteristic BRD4-NUTM1 translocation and a poor prognosis. The primary objective of this study was to describe the clinical and radiologic features, treatment response, and survival of NUT carcinoma (NC). MATERIALS AND METHODS: This retrospective single-center study was based on the review of medical records of NC patients with a specific genetic rearrangement or positive anti-NUT nuclear staining. Overall survival (OS) was analyzed according to primary tumor location. RESULTS: This series of 22 patients had a mean age of 36.27 ± 2.68 years with 68% women and 32% men. The median age at diagnosis was 34 years (range, 17-55 years). The primary tumor was located in the chest (n = 12/22; 55%), head and neck (n = 9/22; 40%), and 1 patient had a renal tumor. About 68% (n = 15/22) patients presented with regional lymph nodal involvement and 77% (n = 17/22) had distant metastases. All the bone metastases were lytic (100%) with mixed lytic and sclerotic metastases in 5 patients. Only 18% (n = 4/22) of the patients showed response to treatment, with progression in the remaining 18 patients. The median OS was 7 months. The OS was significantly (P = 0.024) more in patients with primary head and neck NC (n = 9; OS, 16 months) versus those with pulmonary and other locations (n = 13; OS, 6 months). CONCLUSIONS: Nuclear protein of the testis carcinoma is an aggressive disease refractory to conventional therapy. Imaging with the complementary use of computed tomography, magnetic resonance imaging, and positron emission tomography/computed tomography is important for staging, guiding management, assessing the treatment response, and surveillance.

Factors Impacting Clinically Relevant RNA Fusion Assays Using Next-Generation Sequencing.

CONTEXT.­: RNA-based next-generation sequencing (NGS) assays are being used with increasing frequency for comprehensive molecular profiling of solid tumors. OBJECTIVE.­: To evaluate factors that might impact clinical assay performance. DESIGN.­: A 4-month retrospective review of cases analyzed by a targeted RNA-based NGS assay to detect fusions was performed. RNA extraction was performed from formalin-fixed, paraffin-embedded tissue sections and/or cytology smears of 767 cases, including 493 in-house and 274 outside referral cases. The types of samples included 422 core needle biopsy specimens (55%), 268 resection specimens (35%), and 77 cytology samples (10%). RESULTS.­: Successful NGS fusion testing was achieved in 697 specimens (90.9%) and correlated positively with RNA yield (P < .001) and negatively with specimen necrosis (P = .002), decalcification (P < .001), and paraffin block age of more than 2 years (P = .001). Of the 697 cases that were successfully sequenced, 50 (7.2%) had clinically relevant fusions. The testing success rates and fusion detection rates were similar between core needle biopsy and cytology samples. In contrast, RNA fusion testing was often less successful using resection specimens (P = .007). Testing success was independent of the tumor percentage in the specimen, given that at least 20% tumor cellularity was present. CONCLUSIONS.­: The success of RNA-based NGS testing is multifactorial and is influenced by RNA quality and quantity. Identification of preanalytical factors affecting RNA quality and yield can improve NGS testing success rates.

Utilization of cytology smears improves success rates of RNA-based next-generation sequencing gene fusion assays for clinically relevant predictive biomarkers.

BACKGROUND: The use of RNA-based next-generation sequencing (NGS) assays to detect gene fusions for targeted therapy has rapidly become an essential component of comprehensive molecular profiling. For cytology specimens, the cell block (CB) is most commonly used for fusion testing; however, insufficient cellularity and/or suboptimal RNA quality are often limiting factors. In the current study, the authors evaluated the factors affecting RNA fusion testing in cytology and the added value of smears in cases with a suboptimal or inadequate CB. METHODS: A 12-month retrospective review was performed to identify cytology cases that were evaluated by a targeted RNA-based NGS assay. Samples were sequenced by targeted amplicon-based NGS for 51 clinically relevant genes on a proprietary platform. Preanalytic factors and NGS quality parameters were correlated with the results of RNA fusion testing. RESULTS: The overall success rate of RNA fusion testing was 92%. Of the 146 cases successfully sequenced, 14% had a clinically relevant fusion detected. NGS testing success positively correlated with RNA yield (P = .03) but was independent of the tumor fraction, the tumor size, or the number of slides used for extraction. CB preparations were adequate for testing in 45% cases, but the inclusion of direct smears increased the adequacy rate to 92%. There was no significant difference in testing success rates between smears and CB preparations. CONCLUSIONS: The success of RNA-based NGS fusion testing depends on the quality and quantity of RNA extracted. The use of direct smears significantly improves the adequacy of cytologic samples for RNA fusion testing for predictive biomarkers.

Decoding Genes: Current Update on Radiogenomics of Select Abdominal Malignancies.

Technologic advances in chromosomal analysis and DNA sequencing have enabled genome-wide analysis of cancer cells, yielding considerable data on the genetic basis of malignancies. Evolving knowledge of tumor genetics and oncologic pathways has led to a better understanding of histopathologic features, tumor classification, tumor biologic characteristics, and imaging findings and discovery of targeted therapeutic agents. Radiogenomics is a rapidly evolving field of imaging research aimed at correlating imaging features with gene mutations and gene expression patterns, and it may provide surrogate imaging biomarkers that may supplant genetic tests and be used to predict treatment response and prognosis and guide personalized treatment options. Multidetector CT, multiparametric MRI, and PET with use of multiple radiotracers are some of the imaging techniques commonly used to assess radiogenomic associations. Select abdominal malignancies demonstrate characteristic imaging features that correspond to gene mutations. Recent advances have enabled us to understand the genetics of steatotic and nonsteatotic hepatocellular adenomas, a plethora of morphologic-molecular subtypes of hepatic malignancies, a variety of clear cell and non-clear cell renal cell carcinomas, a myriad of hereditary and sporadic exocrine and neuroendocrine tumors of the pancreas, and the development of targeted therapeutic agents for gastrointestinal stromal tumors based on characteristic KIT gene mutations. Mutations associated with aggressive phenotypes of these malignancies can sometimes be predicted on the basis of their imaging characteristics. Radiologists should be familiar with the genetics and pathogenesis of common cancers that have associated imaging biomarkers, which can help them be integral members of the cancer management team and guide clinicians and pathologists. Online supplemental material is available for this article. ©RSNA, 2020 See discussion on this article by Luna (pp 1627-1630).

Imaging spectrum of NUT carcinomas.

Nuclear protein of the testis (NUT) carcinoma (NC) (formerly known as NUT midline carcinoma) is an aggressive pleomorphic squamous cell carcinoma with a dismal prognosis. Primary NC tumors are commonly located in the chest or head and neck regions. Imaging plays an indispensable role in the staging, management, treatment response assessment, and surveillance of NC. Primary pulmonary NC usually presents as a large mass with lymphadenopathy and pleural involvement. Primary head and neck NC presents as a large expansile necrotic mass in the sinonasal region with locoregional destruction and occasional cervical lymph node involvement. These imaging features are relatively non-specific but are consistent among patients. Currently, there are no standardized guidelines for the treatment of NC. Because of its rarity, paucity of reports in the medical literature, and the lack of awareness among radiologists, NUT carcinoma (NC) has been largely underdiagnosed and misdiagnosed. Clinical aggressive features and pleomorphic/undifferentiated squamous cell carcinoma should prompt genetic evaluation for NUT translocation to diagnose NC. In this article, we discuss NC's clinicopathologic and imaging features and treatment options, including emerging new treatments.