Rhabdomyosarcoma (RMS) encompasses a heterogeneous group of tumors with striated muscle differentiation. RMSs are classified as alveolar, embryonal, spindle cell/sclerosing, and pleomorphic types and ...molecular analysis of these tumors has identified aberrations that are useful in their further subclassification. Spindle cell rhabdomyosarcoma (SpRMS) is uncommon and has been described with VGLL2 fusions, EWSR1/FUS‐TFCP2 rearrangements, and myoD1 mutations—the mutations are associated with significantly different prognoses. In addition, the NCOA2‐MEIS1 fusion gene was recently described in two primary intraosseous RMS that contained spindle cell components. Herein, we report three cases of SpRMS harboring different novel fusion genes, one possessing EP300‐VGLL3, a second with NCOA2‐MEIS1 and CAV1‐MET, and the third case had HMGA2‐NEGR1 and multiple amplified genes.
DEK::AFF2 carcinoma of the sinonasal tract is an emerging entity. The tumor is typically characterized by papillary proliferation of non-keratinizing squamous epithelial cells with monotonous ...cytologic features, which may mimic other sinonasal tumors. The confirmation of this gene fusion has thus far relied solely on next-generation sequencing, fluorescence in situ hybridization (FISH), or reverse transcription polymerase chain reaction (RT-PCR). This current study aimed to validate an immunohistochemical assay for AFF2 C-terminus as an ancillary marker. We first analyzed publicly available RNA sequencing data of sinonasal tumors from the national center for biotechnology information (NCBI) sequence read archive and identified 3 DEK::AFF2 carcinomas out of 28 sinonasal tumors. The gene expression of AFF2 was significantly higher in the fusion-positive cases compared to the wild-type tumors (p < 0.001), while DEK was not. We then optimized an immunohistochemical assay with an anti-AFF2 C-terminus antibody for ancillary diagnosis. Seventeen DEK::AFF2 carcinomas, including 11 cases with predominantly low-grade morphology and one showing glandular differentiation, as well as 78 DEK FISH-negative sinonasal tumors were evaluated by AFF2 immunohistochemistry (IHC). Sixteen of the 17 DEK::AFF2 carcinomas showed nuclear AFF2 expression in ≥30% of tumor cells, including one decalcified case that failed FISH and RT-PCR confirmation. The one case that was negative for AFF2 IHC in the tumor cells also lacked expression in the internal positive control. It was thus considered a failure of the IHC rather than a truly negative case and was excluded from the statistical analysis. All DEK FISH-negative sinonasal tumors were negative for nuclear AFF2 expression. The nuclear expression of AFF2 IHC showed 100% sensitivity and specificity for DEK::AFF2 carcinoma. Accordingly, AFF2 IHC is a highly sensitive and specific ancillary marker that distinguishes DEK-AFF2 carcinoma from the other sinonasal tumors with overlapping morphological features and may be an especially useful alternative for decalcified specimens.
Urine cytology of urinary tract condylomas has not been systematically studied. We analyzed cytologic features of urinary tract condylomas and evaluated potential diagnostic challenges and pitfalls. ...We retrospectively reviewed urine cytology of urinary tract condylomas from 2 academic institutions (2015–2022). Among 20 patients with urinary tract condylomas, 6 had urine cytology (2 samples in 1 patient), including 3 men and 3 women (mean age, 74.3 years; range, 65–86 years). Original interpretations were negative for high-grade urothelial carcinoma (NHGUC; n = 4), atypical urothelial cells (n = 1), reactive urothelial cells (n = 1), and negative for malignancy (n = 1). Squamous cells were noted in 3 cases, atypical squamous cells (ASC) consistent with low-grade squamous intraepithelial lesion (LSIL) were noted in 1 case, and in 3 cases, the presence of squamous cells was not mentioned. All urines were reclassified according to The Paris System as NHGUC. Specimens were composed of benign urothelial cells and groups or isolated ASC consistent with LSIL (n = 4), atypical keratinized squamous cells (n = 2), and ASC that did not meet LSIL criteria (n = 1). The LSIL cells showed nuclear enlargement (n = 4), hyperchromasia (n = 4), perinuclear halo (n = 3), nuclear membrane irregularity (n = 4), orangeophilic cytoplasm (n = 3), and binucleation (n = 4). The atypical keratinized squamous cells showed hyperchromasia (n = 2), nuclear membrane irregularity (n = 2), keratin pearls (n = 2), and binucleation (n = 1). The ASC that did not meet LSIL criteria showed nuclear enlargement and orangeophilic cytoplasm. Many urinary tract condylomas (57%) demonstrate classic LSIL features in urine cytology. Less frequent cases can mimic keratinizing squamous cell carcinoma (28%) or demonstrate ASC not diagnostic of LSIL (15%).
•Urinary tract condylomas are rare and can demonstrate cytologic features of low-grade squamous intraepithelial lesion.•Potential diagnostic pitfalls include a keratinizing squamous cell carcinoma.•The presence of atypical squamous cells in urine cytology should be documented.
Pseudocarcinomatous urothelial hyperplasia (PCUH) architecturally and cytologically mimics cancer. The urine cytology features of PCUH have not been described.
To describe PCUH features in urine ...cytology.
We reviewed urine cytology cases with concurrent PCUH tissue specimens from 5 academic institutions and classified them by using The Paris System criteria.
Thirty-nine patients included 31 men and 8 women with a mean age of 67 years (range, 39-87 years). All patients had prior pelvic irradiation, and most presented with hematuria (n = 27). The specimens included voided urine (n = 16); bladder washing (n = 11); and urine, not otherwise specified (n = 12). The specimen preparation included cytospin (n = 29) and ThinPrep (n = 10). Original interpretations were negative for high-grade urothelial carcinoma (n = 28), atypical urothelial cells (AUCs; n = 10), and high-grade urothelial carcinoma (HGUC; n = 1). Twenty-five urine specimens (64%) had findings of PCUH. These specimens were moderately cellular and composed of sheets, cohesive groups, or isolated urothelial cells. Nucleoli were present in 23 cases. The nuclear membrane was smooth to irregular (n = 9), smooth (n = 8), and irregular (n = 8). The chromatin was glassy (n = 8), vesicular (n = 7), hyperchromatic (n = 7), and vesicular to finely granular (n = 3). The cytoplasm varied from dense squamoid, to finely vacuolated, to vacuolated. Nucleomegaly was observed in all 25 specimens, and nuclear-cytoplasmic ratio greater than 0.5 was seen in 11 of 25 cases (44%). The background contained acute inflammation (n = 14), was clean (n = 9), and contained red blood cells (n = 2). All cases originally interpreted as AUCs and HGUC had PCUH features.
PCUH urine features can overlap with AUCs, HGUC, and other nonurothelial malignancies. In our cohort, 44% (11 of 25) of urine specimens with PCUH changes were initially misclassified. Recognition of cytologic features of PCUH is important to avoid overcalling reactive changes.
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. Accurate and timely diagnosis can potentially inform patient management and guide treatment. While histologic documentation of NC is commonly found, there is a limited description of its cytologic features. A 39-year-old male with a history of sinonasal squamous cell carcinoma (SCC) presented with a right parotid mass aspirated via fine needle aspiration cytology (FNA). Histologic examination of the previous sinonasal pathology reviewed at our institution revealed sheets of primitive-appearing, monotonous, undifferentiated cells with distinct, prominent nucleoli. Additionally, there were foci of abrupt keratinization, accompanied by a notable neutrophilic infiltrate. The initial diagnosis of SCC was reclassified to NC and confirmed through NUT IHC and molecular testing. Although the parotid FNA initially suggested the possibility of a variety of small round blue cell tumors, it exhibited morphological similarities to the sinonasal tumor, leading to the diagnosis of metastatic NC. Cytomorphologic features of NC are limited and can overlap with various small round blue cell tumors. Correct classification is especially pivotal in the era of targeted therapy, considering the ongoing development and evaluation of BET inhibitors targeting BRD4.
Background
Fine‐needle aspiration cytology (FNAC) is generally the initial sampling method for salivary gland neoplasms. The cytomorphologic features of acinic cell carcinoma (AciCC) of salivary ...gland can overlap with other neoplastic and nonneoplastic entities. AciCCs harbor a recurrent t(4;9) rearrangement with upregulation of nuclear receptor subfamily 4 group A member 3 (NR4A3). NR4A3 protein overexpression has been shown to be highly sensitive and specific for the diagnosis of AciCC in histologic specimens and cell block preparations. However, data on NR4A3 immunocytochemistry (ICC) on conventional smears or liquid‐based cytology are limited.
Methods
The authors identified 18 FNAC of histologically proven AciCC cases between 2013 and 2019. FNAC samples of diagnostic mimickers were likewise retrieved and included in the study cohort for comparison. The NOR1/NR4A3 mouse monoclonal antibody was applied directly to FNAC slides using a standard ICC technique.
Results
The cohort included ethanol‐fixed Papanicolaou‐stained cytologic smears and liquid‐based preparations from 18 AciCC, one secretory carcinoma, four mucoepidermoid carcinomas, four salivary duct carcinomas, five pleomorphic adenomas (PA), five Warthin tumors, five oncocytomas, one oncocytic hyperplasia, and five nonneoplastic salivary gland cases. Strong nuclear staining for NR4A3 was present in all AciCC, weak nuclear staining was present in one PA, and all other non‐AciCC were negative (sensitivity, 100%; specificity, 97%).
Conclusions
NR4A3 ICC can be used directly on FNAC conventional smears and liquid‐based cytology to reliably distinguish AciCC from its mimickers. This marker may be useful in cases where a cell block preparation is unavailable or inadequate.
NR4A3 immunocytochemistry can be used directly on fine‐needle aspiration cytology conventional smears and liquid‐based cytology to reliably distinguish acinic cell carcinoma from its mimickers. This may be useful in cases where a cell block preparation is unavailable or inadequate.
Sinonasal myxoma (SNM) is a rare benign mesenchymal tumor that arises in the sinonasal cavity or maxilla and almost exclusively affects young children. Currently, it is considered a specific entity, ...but its molecular characteristics have not been reported. Lesions diagnosed as SNM and odontogenic myxoma/fibromyxoma were identified from the participating institutions, and the clinicopathologic features were recorded. Immunohistochemistry for β-catenin was performed in all cases with available tissue. Next-generation sequencing was performed in all cases with SNM. Five patients with SNM were identified, including 3 boys and 2 girls with an age range of 20-36 months (mean: 26 months). The tumors were well defined, centered in the maxillary sinus, surrounded by a rim of woven bone, and composed of a moderately cellular proliferation of spindle cells oriented in intersecting fascicles in a variably myxocollagenous stroma that contained extravasated erythrocytes. Histologically, the tumors resembled myxoid desmoid fibromatosis. Three tested cases showed nuclear expression of β-catenin. In 3 tumors, next-generation sequencing revealed intragenic deletions of APC exons 5-6, 9 and 15, or 16, respectively, with concurrent loss of the other wild-type copy of APC predicted to result in biallelic inactivation. The deletions were identical to those that occur in desmoid fibromatosis, and copy number analysis raised the possibility that they were germline. In addition, 1 case showed the possible deletion of APC exons 12-14, and another case exhibited a CTNNB1 p. S33C mutation. Ten patients with odontogenic myxoma/fibromyxoma were identified, including 4 women and 6 men (mean age: 42 years). Seven tumors involved the mandible and 3 the maxilla. Histologically, the tumors differed from SNM, and all cases lacked nuclear expression of β-catenin. These findings suggest that SNM represents a myxoid variant of desmoid fibromatosis that often arises in the maxilla. The APC alterations might be germline, and therefore, genetic testing of the affected patients should be considered.
We report the clinicopathologic and immunohistochemical features of 18 cases of confirmed primary synovial sarcoma of the gastrointestinal tract. The neoplasms arose in 10 women and 8 men ranging in ...age from 23 to 81 years (mean: 50; median: 57.5 years). The tumors for which size was known ranged from 1.8 to 15.0 cm (mean: 5.2; median: 5.1 cm). Microscopically, 14 synovial sarcomas were of the monophasic type, 2 were biphasic, and 2 were poorly differentiated. Immunohistochemical analysis of 4 cases showed strong, diffuse staining for SS18::SSX (4/4 cases). Pancytokeratin and EMA immunohistochemistry were performed on 13 and 9 tumors, respectively, and each showed patchy-to-diffuse staining. By reverse-transcription PCR, 3 cases were positive for the SS18::SSX1, and 2 cases were positive for the SS18::SSX2 gene fusion. Six cases contained an SS18 gene rearrangement by fluorescence in situ hybridization, and next-generation sequencing identified an SS18::SSX2 gene fusion in one case. Clinical follow-up information was available for 9 patients (4 months to 4.6 years; mean, 2.8 y; median: 29 months), and one patient had a recent diagnosis. Three patients died of disease within 41 to 72 months (mean, 56 months) of their diagnosis. Five patients were alive without evidence of disease 4 to 52 months (mean, 17.6 months) after surgery; of whom 1 of the patients received additional chemotherapy treatment after surgery because of recurrence of the disease. A single patient was alive with intraabdominal recurrence 13 months after surgery. We conclude that synovial sarcoma of the gastrointestinal tract is an aggressive tumor, similar to its soft tissue counterpart, with adverse patient outcomes. It is important to distinguish it from morphologically similar gastrointestinal tract lesions that may have different treatment regimens and prognoses.
Background. Metastatic clear cell renal cell carcinoma (RCC) is one of the most common secondary thyroid malignancies. Diagnosis can be challenging, particularly if presenting many years after ...initial diagnosis. We reviewed clinicopathologic features and immunoprofile of metastatic clear cell RCC in thyroid. Design. We identified 17 patients from 2003-2021. Clinical data were obtained from medical records, and slides were retrieved and reviewed. Results. Seventeen patients (12 male and 5 female) included 12 thyroidectomies, 3 core biopsies, 1 excisional biopsy, and 1 fine-needle aspiration. The average patient age was 68.7 years (range, 45-88 years). Sixteen patients had history of clear cell RCC, and in 1 patient, the clear cell RCC was discovered after the thyroid metastasis was found. Thyroid gland metastases were on average diagnosed 90.7 months after the diagnosis of the renal primary (range, 24-240 months). Patients presented with a new palpable mass (n = 11) or dyspnea/stridor (n = 1). Five tumors were incidentally found via surveillance imaging. In 2 patients, metastases occurred within follicular thyroid neoplasms. All metastases showed conspicuous sinusoidal vasculature between the tumor nests and areas of myxoid degeneration. A prominent thick fibromuscular pseudocapsule was evident in 10 resections. Immunohistochemistry (n = 5) showed that the metastases were positive for PAX8, CA9, and CD10, while negative for keratin 7, thyroglobulin, and TTF1. Conclusions. Metastatic clear cell RCC involving the thyroid gland is infrequent and typically occurs remotely after the initial diagnosis. Cytologic and histologic features may show significant overlap with primary thyroid lesions. Immunohistochemistry can help reliably distinguish metastases from primary thyroid neoplasms.
