Inflammatory leiomyosarcoma/rhabdomyoblastic tumor: A report of two cases with novel genetic findings.

Inflammatory leiomyosarcoma (ILMS) is a malignant neoplasm showing smooth muscle differentiation, a prominent inflammatory infiltrate, and near-haploidization. These tumors have significant pathologic and genetic overlap with the recently described "inflammatory rhabdomyoblastic tumor (IRT)," suggesting that ILMS and IRT may belong to one entity. Herein, we describe two cases of ILMS/IRT with attention to new cytogenetic and sequencing findings. The tumors were composed of sheets and fascicles of variably pleomorphic tumor cells showing spindled and epithelioid to rhabdoid morphology and a prominent histiocyte-rich inflammatory infiltrate typical of ILMS/IRT. In case 1, chromosomal microarray analysis showed a near-haploid pattern with loss of heterozygosity resulting from loss of one copy of all autosomes except for chromosomes 5, 20, 21, and 22. Case 2 showed areas with high-grade rhabdomyosarcomatous transformation. In this case, the low-grade tumor component revealed a hyper-diploid pattern with loss of heterozygosity for most of autosomes but with a normal diploid copy number state except for chromosomes 5, 20, and 22, which showed a relative gain. The high-grade tumor component showed a similar pattern of copy-neutral loss of heterozygosity with additional abnormalities, including mosaic segmental gains at 1p, 5p, 8q, 9p, 20q, and segmental loss at 8p. Next-generation sequencing identified sequence variants in NF1, TP53, SMARCA4, KRAS, and MSH6. MSH6 variant was confirmed as germline, consistent with the diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC) syndrome in one of our study patients and suggestive that ILMS/IRT might be part of the HNPCC cancer spectrum.

Combinations of Chemotherapy and PD-1/PD-L1 Inhibitors in Sarcoma.

OPINION STATEMENT: While no PD-1 inhibitor has been FDA approved for use in sarcoma or proven efficacious in a randomized trial, the use of single agent PD-1 inhibitors is standard-of-care and recommended by the NCCN guidelines in certain specific subtypes and situations. Even while the role of immunotherapy is still being defined in sarcoma, there is rising interest in combinations of PD-1 inhibitors with standard-of-care treatments, especially chemotherapy. Recently, several early phase trials have suggested potential benefits for chemotherapy in combination with PD-1 inhibitors. Although some physicians are already combining PD-1 inhibitors and chemotherapy for sarcoma off-label in the community, we believe more data is necessary. We support further evaluation of these combinations in well-designed clinical trials.

Kikuchi-Fujimoto disease presenting in a patient with SARS-CoV-2: a case report.

BACKGROUND: We present a yet to be described association of SARS-CoV-2 infection with Kikuchi-Fujimoto disease. CASE PRESENTATION: A 32-year-old physician with history of SARS-CoV-2 infection presented to the emergency department with 2 weeks of fever, chills, and right sided cervical lymphadenopathy. He was treated empirically for presumed folliculitis with worsening of symptoms leading to repeat presentation to the emergency department. Extensive workup was unrevealing of an infectious cause and needle biopsy of the lesion was unrevealing. An excisional lymph node biopsy revealed follicular hyperplasia with necrotic foci showing abundance of histiocytes at the edge of necrosis with CD8 predominance of T-cells. Final diagnosis was deemed to be Kikuchi-Fujimoto disease. Antibiotic therapy was discontinued, and the patient's symptoms resolved with steroid therapy and expectant management. CONCLUSIONS: This is the first report of a patient developing Kikuchi-Fujimoto disease following SARS-CoV-2 infection. Clinicians should be aware of Kikuchi-Fujimoto disease as a possibility when approaching patients with hyper-inflammatory states who present with cervical lymphadenopathy.

In situ hybridization for high risk HPV E6/E7 mRNA in oropharyngeal squamous cell carcinoma.

OBJECTIVES: To report a single institution's experience using human papillomavirus (HPV) E6/E7 mRNA in-situ hybridization (mRNA ISH) for HPV detection in oropharyngeal squamous cell carcinoma (OPSCC). To review the literature on HPV detection methods. STUDY DESIGN: Retrospective chart review, literature review. SETTING: Tertiary care academic hospital. SUBJECTS AND METHODS: We conducted a retrospective chart review of 122 OPSCC biopsy specimens. mRNA ISH was performed on formalin-fixed paraffin-embedded (FFPE) tissue with a pool of 18 high risk HPV probes using an automated stainer; p16 immunohistochemistry (IHC) was also performed. We conducted a literature review on HPV detection methods including p16 IHC, mRNA ISH, DNA ISH, and PCR. RESULTS: In our cohort, mRNA ISH had a sensitivity and specificity of 100% and 100% with reference to p16 (100% concordance). 2-year OS was 87.5% vs. 94.5% for p16/HPV-negative vs. positive patients. 2-year DFS was 60.0% vs. 84.2%. On literature review, mRNA ISH demonstrated consistently high sensitivity and specificity ranging from 88-98% and 90-100% respectively. In comparison, the specificity of p16 was 85-95%. CONCLUSIONS: Our report supports the use of mRNA ISH for HPV detection in OPSCC and validates its feasibility using automated tissue staining methods on FFPE tissue. Our findings and literature review support that mRNA ISH may have superior specificity and be easier to interpret than p16. Further study on the prognostic value and cost-effectiveness of mRNA ISH is warranted and may establish this HPV detection method as the "gold standard."

Uncommon molecular alterations in follicular-derived thyroid carcinoma: A single institution study.

Thyroid carcinomas are the most common endocrine malignancy and commonly have alterations in the mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3 kinase (PI3K)/AKT signaling pathways in well-differentiated tumors. Alternative molecular alterations driving thyroid carcinomas have been identified rarely in the literature and are more likely to occur in poorly differentiated or anaplastic cases. In this study, uncommon genetic alterations such as MLH1, MSH2, NSD3::NUTM1, RET::SPECC1L, and G3BP2::FGFR2 were identified in patients with papillary thyroid carcinoma, poorly differentiated thyroid carcinoma, and differentiated high-grade thyroid carcinoma. Most of these tumors demonstrated an aggressive biological behavior. Atypical driver mutations in thyroid carcinomas can occur in patients with cancer predisposition syndromes as demonstrated by an NTRK1::TPM3 fusion in a patient with Li Fraumeni syndrome. In these settings of more aggressive disease, molecular testing targeting actionable fusions and mutations is important. As demonstrated in our case cohort, 100% of cases diagnosed as high-grade follicular-derived thyroid carcinoma had a mutation or fusion that is associated with worse prognosis, has a germline syndrome association requiring further work up, or an actionable mutation. This high yield seen in this cohort for molecular testing in patients with high-grade follicular-derived thyroid carcinoma suggests more routine molecular testing in this population would be a beneficial clinical practice.

Clear cell chondrosarcoma: a review of clinicopathologic characteristics, differential diagnoses, and patient management.

Clear cell chondrosarcoma (CCC), an extremely rare primary bone tumor, is currently classified by the World Health Organization as a low-grade malignant cartilaginous neoplasm. Clinically, CCC occurs primarily in males with a peak incidence in the third to fifth decades of life, and occasionally, it presents in skeletally immature patients. Unlike conventional chondrosarcoma, CCC has a predilection for the epiphysis of long bones and often displays radiologic features reminiscent of chondroblastoma. The recommended treatment is wide operative resection. CCC has a local recurrence rate of approximately 30%, and nearly 20% cases metastasize mainly to bone and lung often a decade after surgical intervention. Incomplete excision or curettage is associated with a high rate of recurrence. Histologically, the process is characterized by infiltrative lobules and sheets of round to oval cells with abundant cleared cytoplasm and well-defined cell borders associated with trabecula of osteoid and woven bone, scattered osteoclasts, and foci of conventional low-grade chondrosarcoma in about one-half of cases. Correlation with clinical and radiologic characteristics, such as epiphyseal location and young patient age, assists in establishing a correct diagnosis. Pathologic diagnosis of CCC is complicated by the low diagnostic accuracy of core needle biopsy, overlapping histologic features with other matrix-rich primary bone tumors, and a lack of a specific immunohistochemical and molecular profile. DNA methylation-based profiling classifier (sarcoma classifier) is one recent technologic advancement that may help to confirm the histopathological diagnosis of CCC or indicate the need for thorough reassessment in cases where results contradict previous conventional findings.

Toll-Like Receptor 4 Agonist Injection With Concurrent Radiotherapy in Patients With Metastatic Soft Tissue Sarcoma: A Phase 1 Nonrandomized Controlled Trial.

Importance: Metastatic soft tissue sarcomas (STSs) have limited systemic therapy options, and immunomodulation has not yet meaningfully improved outcomes. Intratumoral (IT) injection of the toll-like receptor 4 (TLR4) agonist glycopyranosyl lipid A in stable-emulsion formulation (GLA-SE) has been studied as immunotherapy in other contexts. Objective: To evaluate the safety, efficacy, and immunomodulatory effects of IT GLA-SE with concurrent radiotherapy in patients with metastatic STS with injectable lesions. Design, Setting, and Participants: This phase 1 nonrandomized controlled trial of patients with STS was performed at a single academic sarcoma specialty center from November 17, 2014, to March 16, 2016. Data analysis was performed from August 2016 to September 2022. Interventions: Two doses of IT GLA-SE (5 µg and 10 µg for 8 weekly doses) were tested for safety in combination with concurrent radiotherapy of the injected lesion. Main Outcomes and Measures: Primary end points were safety and tolerability. Secondary and exploratory end points included local response rates as well as measurement of antitumor immunity with immunohistochemistry and T-cell receptor (TCR) sequencing of tumor-infiltrating and circulating lymphocytes. Results: Twelve patients (median [range] age, 65 [34-78] years; 8 [67%] female) were treated across the 2 dose cohorts. Intratumoral GLA-SE was well tolerated, with only 1 patient (8%) experiencing a grade 2 adverse event. All patients achieved local control of the injected lesion after 8 doses, with 1 patient having complete regression (mean regression, -25%; range, -100% to 4%). In patients with durable local response, there were detectable increases in tumor-infiltrating lymphocytes. In 1 patient (target lesion -39% at 259 days of follow-up), TCR sequencing revealed expansion of preexisting and de novo clonotypes, with convergence of numerous rearrangements coding for the same binding sequence (suggestive of clonal convergence to antitumor targets). Single-cell sequencing identified these same expanded TCR clones in peripheral blood after treatment; these T cells had markedly enhanced Tbet expression, suggesting TH1 phenotype. Conclusions and Relevance: In this nonrandomized controlled trial, IT GLA-SE with concurrent radiotherapy was well tolerated and provided more durable local control than radiotherapy alone. Patients with durable local response demonstrated enhanced IT T-cell clonal expansion, with matched expansion of these clonotypes in the circulation. Additional studies evaluating synergism of IT GLA-SE and radiotherapy with systemic immune modulation are warranted. Trial Registration: ClinicalTrials.gov Identifier: NCT02180698.

Diagnosis of giant cell-rich bone tumors on core needle biopsy: A practical approach.

BACKGROUND: The differential diagnosis of giant cell-rich bone tumors comprises a broad spectrum of lesions with prominent reactive osteoclast-like and/or neoplastic giant cells, with substantial differences in biologic behavior and clinical management. Evaluation of giant cell-rich bone tumors on small biopsies can be challenging especially in specimens with limited representative material. An accurate diagnosis requires a high level of skill on the part of both radiologist and pathologist as correlation with clinical and radiologic characteristics is critical. The objective of the study was to assess the utility of touch preparations (TP), immunohistochemistry (IHC) for mutation-specific markers H3G34W and H3K36M, and fluorescence in situ hybridization (FISH) for USP6 rearrangements and MDM2 amplification in the diagnostic workup of core needle biopsy specimens. METHODS: A total of 27 core needle biopsies with TPs from patients with primary giant cell-rich bone tumors (16 giant cell tumors of bone (GCTBs) (including 3 with lung metastasis), 3 chondroblastomas (CBs), 4 primary aneurysmal bone cysts (ABCs), 2 non-ossifying fibromas (NOFs), 1 low grade osteosarcoma (OS), and 1 conventional OS with tumor giant cells were analyzed with IHC for H3G34W and H3K36M and in select cases FISH for USP6 rearrangements and MDM2 amplification. RESULTS: In all cases the core biopsies were sufficient for histologic examination and diagnostic workup. 16 of 16 GCTBs were positive for H3G34W and negative for H3K36M, and 3 of 3 CBs were positive for H3K36M and negative for H3G34W. All other cases were negative for H3G34W and H3K36M. 4 of 4 primary ABCs showed rearrangement of USP6 by FISH and the low grade OS showed amplification of MDM2 by FISH. CONCLUSIONS: On-site adequacy assessment of TPs proved to be an accurate, simple, and fast method for obtaining sufficient material for complete diagnostic workup. The application of IHC for H3G34W and H3K36M and FISH for detection of rearrangements of USP6 and amplification of MDM2 can improve the diagnostic accuracy in core needle biopsy specimens.

Histologic Variants of Kaposi Sarcoma in the Gastrointestinal Tract: A Contemporary Multi-institutional Clinicopathologic Analysis of 46 Cases.

Kaposi sarcoma (KS) can pose diagnostic challenges in biopsy specimens. Multiple histologic variants of cutaneous KS have been described; however, the histomorphologic spectrum of gastrointestinal (GI) KS has not been systematically studied. This large series comprehensively evaluated 46 cases of KS involving the GI tract and identified 7 histomorphologic variants, some that have not been previously described. Five of them are inconspicuous but have unique morphologic patterns, including lymphangioma/lymphangiectatic-like (n=17), mucosal hemorrhage/telangiectatic-like (n=17), mucosal inflammation-like (n=15), granulation tissue-like (n=13), and mucosal prolapse-like (n=4) variants. These variants can be easily misdiagnosed or misinterpreted on routine examination if KS is not considered, and if the immunohistochemical stain for human herpesvirus-8 is not performed. The other 2 morphologic variants present as spindle cell proliferations and are the GI stromal tumor-like (n=8) and inflammatory myofibroblastic tumor-like (n=2). These variants raise a broad differential diagnosis of spindle cell tumors of the GI tract and could pose diagnostic challenges. In summary, GI KS lesions exhibit variable, often unconventional histomorphologic patterns. KS should be included in the differential diagnosis even if features of conventional KS are not seen, particularly in limited biopsies in immunocompromised patients, such as those with human immunodeficiency virus infection. Although the clinical significance of these morphologic variants is yet to be determined, they are nonetheless important from a diagnostic standpoint. Misdiagnosis and delay in appropriate management can be avoided by recognizing the morphologic diversity of GI KS and appropriately utilizing the human herpesvirus-8 immunohistochemical stain.

Immunologic Gene Signature Analysis Correlates Myeloid Cells and M2 Macrophages with Time to Trabectedin Failure in Sarcoma Patients.

Patients with metastatic soft tissue sarcoma (STS) have a poor prognosis and few available systemic treatment options. Trabectedin is currently being investigated as a potential adjunct to immunotherapy as it has been previously shown to kill tumor-associated macrophages. In this retrospective study, we sought to identify biomarkers that would be relevant to trials combining trabectedin with immunotherapy. We performed a single-center retrospective study of sarcoma patients treated with trabectedin with long-term follow-up. Multiplex gene expression analysis using the NanoString platform was assessed, and an exploratory analysis using the lasso-penalized Cox regression and kernel association test for survival (MiRKAT-S) methods investigated tumor-associated immune cells and correlated their gene signatures to patient survival. In total, 147 sarcoma patients treated with trabectedin were analyzed, with a mean follow-up time of 5 years. Patients with fewer prior chemotherapy regimens were more likely to stay on trabectedin longer (pairwise correlation = -0.17, p = 0.04). At 5 years, increased PD-L1 expression corresponded to worse outcomes (HR = 1.87, p = 0.04, q = 0.199). Additionally, six immunologic gene signatures were associated with up to 7-year survival by MiRKAT-S, notably myeloid-derived suppressor cells (p = 0.023, q = 0.058) and M2 macrophages (p = 0.03, q = 0.058). We found that the number of chemotherapy regimens prior to trabectedin negatively correlated with the number of trabectedin cycles received, suggesting that patients may benefit from receiving trabectedin earlier in their therapy course. The correlation of trabectedin outcomes with immune cell infiltrates supports the hypothesis that trabectedin may function as an immune modulator and supports ongoing efforts to study trabectedin in combination with immunotherapy. Furthermore, tumors with an immunosuppressive microenvironment characterized by macrophage infiltration and high PD-L1 expression were less likely to benefit from trabectedin, which could guide clinicians in future treatment decisions.

B7-H3 Specific CAR T Cells for the Naturally Occurring, Spontaneous Canine Sarcoma Model.

One obstacle for human solid tumor immunotherapy research is the lack of clinically relevant animal models. In this study, we sought to establish a chimeric antigen receptor (CAR) T-cell treatment model for naturally occurring canine sarcomas as a model for human CAR T-cell therapy. Canine CARs specific for B7-H3 were constructed using a single-chain variable fragment derived from the human B7-H3-specific antibody MGA271, which we confirmed to be cross-reactive with canine B7-H3. After refining activation, transduction, and expansion methods, we confirmed target killing in a tumor spheroid three-dimensional assay. We designed a B7-H3 canine CAR T-cell and achieved consistently high levels of transduction efficacy, expansion, and in vitro tumor killing. Safety of the CAR T cells were confirmed in two purposely bred healthy canine subjects following lymphodepletion by cyclophosphamide and fludarabine. Immune response, clinical parameters, and manifestation were closely monitored after treatments and were shown to resemble that of humans. No severe adverse events were observed. In summary, we demonstrated that similar to human cancers, B7-H3 can serve as a target for canine solid tumors. We successfully generated highly functional canine B7-H3-specific CAR T-cell products using a production protocol that closely models human CAR T-cell production procedure. The treatment regimen that we designed was confirmed to be safe in vivo. Our research provides a promising direction to establish in vitro and in vivo models for immunotherapy for canine and human solid tumor treatment.

Synovial sarcoma with overwhelming glandular (adenocarcinoma-like) component: A case report and review of the literature.

Synovial sarcoma is an uncommon tumor of soft tissue, characterized by a specific SS18-SSX1/2/4 fusion gene. It is generally a lesion composed of monomorphic spindle cells, and can sometimes show variable epithelial differentiation. Here, we present the case of a young woman with a synovial sarcoma of the abdominal wall that showed an overwhelming (>90 %) epithelial glandular component mimicking adenocarcinoma, and only rare spindled areas. The diagnosis was confirmed by detection of targeted fusion transcripts associated with synovial sarcoma. We review the literature pertaining to synovial sarcoma, and we show that this case is only the sixth molecularly proven epithelial predominant synovial sarcoma in the literature. This report emphasizes the importance of molecular approaches in modern soft tissue pathology. Recognition of synovial sarcoma with predominant glandular component is imperative in order to avoid misdiagnosis of the tumor as metastatic adenocarcinoma, another type of sarcoma with epithelial differentiation, or a carcinoma with a sarcomatous component (sarcomatoid carcinoma), all of which have markedly different clinical management.

Solitary fibrous tumor of thoracic cavity, extra-thoracic sites and central nervous system: Clinicopathologic features and association with local recurrence and metastasis.

Published risk stratification models of solitary fibrous tumor (SFT) have been associated with distant metastases outside the central nervous system (CNS), but have not been studied for tumors occurring in the CNS. In a retrospective review, we identified 72 cases of solitary fibrous tumor or hemangiopericytoma (HPC) diagnosed between January 2011 and December 2020 at our institution. The tumors involved the central nervous system (N = 17), thoracic cavity (N = 28), and extrathoracic sites (N = 27). The risk of local recurrence, distant metastasis, or death at 5 years was 57% (95% CI 23%, 76%) in the CNS, 24% (95% CI 2%, 41%) in the thoracic cavity, and 13% (95% CI 0%, 25%) in extrathoracic sites. By contrast, the risk of distant metastasis or death at 5 years was 13% (95% CI 0%, 29%) in CNS primaries, 5% (95% CI 0%, 14%) in thoracic primaries, and 14% (95% CI 0%, 27%) in extrathoracic primaries. Using the published 3- and 4-variable risk stratification models by Demicco et al., we retrospectively assessed our cases for risk of local recurrence, distant metastasis, and death. For tumors outside the CNS, we show that three- and four-variable risk stratification models were associated with recurrence-free survival in addition to the previously known association with distant metastasis (all P < 0.05). In contrast, inside the CNS, we show that neither risk model is a significantly associated with clinical behavior, and that WHO grade is likely the best available prognostic tool, though none of the differences were significant. The lack of significant differences can be likely explained by the younger median age (47 years vs 61 years) and smaller median tumor size (3.5 cm vs 5.6 cm), downgrading the risk stratification scores in CNS compared to non-CNS primaries. In conclusion, existing risk stratification models of SFT are not associated with clinical behavior for tumors arising inside the CNS, but are associated with local recurrence in addition to distant metastasis outside the CNS.

High-risk human papillomavirus-mediated adenocarcinoma of palatine tonsil.

We describe the case of a human papillomavirus-mediated adenocarcinoma of palatine tonsil in a 51-year-old male. Histologically, the tumor exhibited a predominantly cribriform and tubular (glandular) growth of cuboidal and columnar cells with moderate amount of pale eosinophilic cytoplasm and oval or spindled nuclei with finely dispersed or coarse chromatin and small to medium-sized nucleoli. Foci of nuclear anaplasia and multinucleation, numerous mitotic figures, and necrosis (individual-cell and confluent) were seen. No squamous differentiation was identified. The tumor cells showed strong expression of CK7, p16 and HPV E6/E7 mRNA transcripts, and were negative for p40, CK5/6, AR, synaptophysin and chromogranin. Next generation sequencing showed 3 variants of unknown significance: FGF3 p.(R44fs); NF1 p.(S749 L) and POLE p. (S1506 L) with variant allele frequencies of 37 %; 20 %, and 17 % respectively. Chromosomal microarray analysis using single nucleotide polymorphism microarray (OncoScan) assay showed whole chromosomal gains of chromosomes 8 and 19, whole chromosomal losses of chromosomes 2 and 16, as well as segmental gains of chromosomes 3q25.31q29 (encompassing the PIK3CA gene), 17q21.31q25.3, 20p13q13.33, Xq28, and segmental losses of chromosomes 1q32.2, 6p25.1p21.1, 11q23.1q24.1, 12p11.22, 12p11.22, 14q24.1q32.33, 17p13.3q21.31 (encompassing the TP53 and NF1 genes). The results highlight the need to consider HPV testing in non-squamous cell carcinomas of the oropharynx.

Probable neurosarcoidosis presenting as acute on chronic otorrhoea: a difficult diagnosis.

An elderly African American woman presented to our clinic following 9 months of right-sided unilateral headache, otorrhoea and progressive hearing loss. Despite treatment with topical and oral antibiotics, her clinical condition worsened, and imaging showed mastoid coalescence with an associated subgaleal abscess. She underwent right mastoidectomy and was discharged 3 days later on broad-spectrum intravenous antibiotics despite negative operative cultures. Six weeks later, she was hospitalised with diplopia secondary to a right lateral rectus palsy. Imaging showed abscess resolution but progressive bony remodelling and enhancement of the lateral extending into anterior skull base. Chest CT demonstrated upper lobe predominant pulmonary micronodules, and mastoid biopsy on revision surgery was notable for non-caseating granulomas. Further extensive work-up could not identify an alternative cause, and a presumptive diagnosis of neurosarcoidosis was made. The patient was initiated on intravenous steroids, experienced symptomatic improvement and was thereafter transitioned to oral steroid taper on discharge.

Oropharyngeal carcinoma: A single institution study of 338 primaries with special reference to high-risk human papillomavirus-mediated carcinoma with aggressive behavior.

In a retrospective review, we identified 332 patients with 338 pathologically diagnosed primary oropharyngeal carcinomas (OPC) between January 2013 and March 2020 with known p16/HPV status from a tumor registry at Northwestern Memorial Hospital. The tumors predominantly involved the palatine tonsil (51 %) and the base of the tongue/lingual tonsil (38 %). The most common type of cancer was non-keratinizing squamous cell carcinoma (60 %), and the majority of primaries were p16 positive/HPV-mediated (86 %). A cohort of p16 positive/HPV mediated OPC (27/283, 9.5 %) presented with aggressive clinical behavior, including multiple distant metastases at unusual sites. Tumor size >2 cm and the presence of tumor anaplasia/multinucleation were significantly associated with an increased rate of distant metastases in p16 positive/HPV mediated cases, both in unadjusted and adjusted analyses (all P < 0.05). Of the 332 individuals in the overall cohort, 38 individuals died due to their disease within the observed follow-up time. Among the 283 patients with p16 positive/HPV mediated tumors, survival was estimated at 97 % (95 % CI 95 %, 100 %) at 1 year, 95 % (95 % CI 92 %, 98 %) at 2 years, and 80 % (95 % CI 72 %, 89 %) at 5 years. The presence of tumor anaplasia/multinucleation and distant metastasis were both significantly associated with poorer disease-specific survival in p16 positive/HPV mediated cases (both P < 0.05), with the survival effect of tumor anaplasia/multinucleation likely mediated in part through its association with distant metastasis. For p16 positive/HPV-mediated OPC, age, smoking status, tumor status, and lymph node status were not significantly associated with disease-specific survival in our study.

Ewing sarcoma with myxoid stroma: Case report of an unusual histological variant.

We describe the case of a Ewing sarcoma with prominent myxoid stroma of the temporal bone in a 26-year-old female. Histologically, the tumor exhibited a fascicular growth pattern of round to spindled cells with a minimal amount of pale eosinophilic to clear cytoplasm and oval or spindled nuclei with finely dispersed chromatin and small nucleoli. Myxoid changes were prominent (>50%), with reticular or pseudoacinar growth of the loosely cohesive cells. The tumor showed strong expression of CD99, FLI1, and CD56 and was positive for the EWSR1-FLI1 fusion transcript. The diagnosis of Ewing sarcoma with myxoid stroma (myxoid variant) is particularly problematic owing to the large number of potential mimics. The tumor extends the morphologic spectrum of Ewing sarcoma beyond the previously described histological variants, and broadens the differential diagnosis. For any round/spindle cell sarcoma, prominent myxoid stroma and CD99 immunoreactivity should prompt consideration for molecular studies that include analysis of both EWSR1 and FLI1.

Sinonasal glomangiopericytoma: A clinicopathologic study.

Sinonasal glomangiopericytoma (SNGP) is a neoplasm arising in the nasal cavity and paranasal sinuses that shows perivascular myoid differentiation. The diagnosis of SNGP may be diagnostically challenging due to a large number of potential mimics. In the present study, we sought to characterize the histological and molecular features of six cases of SNGP found in prior surgical pathology records over a 15-year period. The average age at diagnosis was 48.5 years (range: 31-78 years), and the male-to-female ratio was 1:1. Imaging studies in all six cases demonstrated avidly enhancing, lobulated soft tissue masses in the nasal cavity, extending into the sinuses and nasopharynx. Histologically, the tumors were unencapsulated and composed of a proliferation of closely packed, bland, and uniform spindle cells growing deep to an intact surface respiratory epithelium. The cells were separated by a distinctive vascular network ranging from capillaries to large vascular spaces. All cases demonstrated strong positivity for smooth muscle actin, cyclin D1, CD99, and ß-catenin (100%). Targeted sequencing revealed recurrent CTNNB1 missense mutations in all cases tested. Additionally, TLE1 was positive in all cases which has not been previously reported. No tested cases harbored SS18 translocations. We found that while no single marker resolves immunohistochemical overlap between SNGP and its histologic mimics, an extended immunohistochemical panel that includes ß-catenin, cyclin D1, STAT6, smooth muscle actin, pan-cytokeratin cocktails, S100, and SOX10 helps to support the diagnosis of SNGP in diagnostically challenging cases without the need for molecular studies.

Ectopic hamartomatous thymoma in an immunocompromised male.

Ectopic hamartomatous thymoma (EHT) is a rare benign neoplasm classically occurring in the lower neck of adult males. Here we present a case of EHT occurring in a 43-year-old immunocompromised male and a brief review of existing literature. The patient presented with a palpable mass overlying the left clavicle which, on imaging, showed a solitary nodule possibly eroding the cortical bone. A biopsy predominantly showed spindle cells that were immunopositive for keratin AE1/AE3 as well as weakly positive for CD99, SMA, and CD34. A diagnosis of synovial sarcoma was favored; at which point surgical resection was performed. The resected mass was well-demarcated with a tan-yellow cut surface. Microscopically, the lesion was composed of a mixture of spindle cells, glands, and mature adipose tissue. The spindle cells were plump with bland nuclei, and the epithelial component showed morphology similar to glands of salivary or breast tissue with a bilayered appearance (luminal and basal). No pleomorphism, mitotic figures, or necrosis was present. Immunohistochemical stains were performed and showed the spindle cells to express a myoepithelial phenotype (cytokeratin AE1/AE3, p63, calponin positive). The glands showed SMA and p63 positivity in the basal cells (similar to salivary gland and breast). Overall, given the clinical context, histomorphologic, and immunohistochemical profile, a diagnosis of EHT was made. At 12 months of follow-up there was no evidence of recurrence.

Pathology of Melanotic Schwannoma.

CONTEXT.­: Melanotic schwannoma (MS) is a nerve sheath tumor with a uniform composition of variably melanin-producing Schwann cells and metastatic potential. The MS is an uncommon neoplasm, accounting for less than 1% of all nerve sheath tumors, with a predilection for spinal nerve involvement. Microscopically, the tumors are characterized by spindle and epithelioid cells arranged in interlacing fascicles, with marked accumulation of melanin in neoplastic cells and associated melanophages. The MSs are frequently associated with Carney complex, showing features of psammoma bodies and adipose-like cells. Strict criteria of malignancy in MS are not well developed, although a combination of worrisome histologic features (large, vesicular nuclei, with macronucleoli, brisk mitotic activity, and necrosis) raises concern for aggressive behavior. OBJECTIVE.­: To review the current status of the MS literature, discussing putative etiology, histopathology, current genetics, and differential diagnoses, including overlap with other pigmented tumors. DATA SOURCES.­: Search of PubMed (National Center for Biotechnology Information, Bethesda, Maryland) and the authors' own experiences. CONCLUSIONS.­: The occurrence of MS at several unusual anatomic sites and its spectrum of morphologic patterns can result in significant diagnostic difficulty, and correct diagnosis is particularly important because of its high tendency to recur locally and to metastasize, which highlights the importance of diagnostic recognition, ancillary molecular genetic testing, and close clinical follow-up of patients with MS.