Myoepithelial Tumors of Bone with EWSR1::PBX3 Fusion: A Spectrum from Benign to Malignant.

The EWSR1::PBX3 fusion gene, commonly associated with cutaneous syncytial myoepitheliomas, is also found in myoepithelial tumors (METs) of bone and soft tissue. These tumors typically demonstrate benign histology and favorable outcomes. This study examines six previously unreported intraosseous METs harboring the EWSR1::PBX3 fusion, focusing on their histopathologic characteristics, immunophenotype, clinical and radiographic profiles, and patient outcomes. The cohort comprised five males and one female, aged 25 to 65 years (median age 31), with tumors located in the proximal tibia (three cases), distal radius (two cases), and ilium (one case), and sizes between 3.2 to 12.2 cm (median size 3.9 cm). Imaging showed osteolytic lesions with varying degrees of cortical involvement and soft tissue extension in three cases. Histologically, four tumors showed mainly uniform oval-to-spindled cells in syncytial or fascicular arrangements within a collagenous matrix, displaying either bland nuclear features or mild atypia, and low to slightly elevated mitotic activity (≤1 per 10 HPF in three cases and 6 per 10 HPFs in one), classifying them as benign or atypical METs. In contrast, two tumors exhibited pronounced nuclear atypia with ovoid, spindled, epithelioid and round cells, hyperchromatic nuclei, inconspicuous nucleoli, increased N/C ratios, high mitotic rates (17 and 19 per 10 HPFs), and extensive necrosis. Both tumors behaved aggressively-one patient underwent amputation after neoadjuvant chemotherapy and radiation, while the other died with the disease. Immunohistochemically, the tumors consistently expressed EMA and S100, but lacked keratin (AE1/AE3) expression. Our study demonstrates that bone METs with EWSR1::PBX3 fusions encompass a histologic continuum from benign to malignant, with benign/atypical METs mirroring their cutaneous analogs in morphology and malignant variants distinguished by heterogenous cytologic and architectural features, pronounced nuclear atypia, and high mitotic rates.

Thoracic SMARCA4-Deficient Undifferentiated Tumors With Unusual Presentations: A Case Series.

CONTEXT: Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a recently described aggressive neoplasm of young smokers defined by SMARCA4 inactivating mutations and characterized by cells with rhabdoid morphology, high mitotic activity, and abundant necrosis. OBJECTIVE: Describe and compare 3 unusual presentations of SMARCA4-UT in older adults, including one presenting as a metastatic lesion mimicking a primary bone sarcoma. Discuss the molecular characteristics of SMARCA4-UT and their relationship to nonsmall-cell lung carcinomas with SMARCA4. DESIGN: Three patients with SMARCA4-UTs were identified utilizing a natural language search in CoPath. hematoxylin and eosin sections from all patients as well as Papanicolaou-stained slides and Diff-Quik-stained slides for the first patient were examined. A broad range of immunostains, including BRG1/SMARCA4, were evaluated. Molecular testing was performed via next-generation sequencing. RESULTS: The 3 patients were aged 58, 70, and 70 years. All had a significant smoking history. The first patient presented with an iliac bone mass and mediastinal lymphadenopathy, the second with mediastinal adenopathy, and the third with a paratracheal mass. All 3 tumors showed a diffuse proliferation of pleomorphic, rhabdoid cells with high mitotic activity and tumor necrosis. SMARCA4 was lost in all 3 tumors by immunohistochemistry. Molecular testing revealed SMARCA4 alterations in the first 2. CONCLUSIONS: Thoracic SMARCA4-UT should be considered in the differential diagnosis of pleomorphic rhabdoid tumors in older adults with a smoking history. Although most present as lung and/or mediastinal masses, they may occasionally present as a metastasis and mimic an undifferentiated sarcoma, representing a potential diagnostic pitfall.

Appropriate use criteria for ancillary diagnostic testing in dermatopathology: New recommendations for 11 tests and 220 clinical scenarios from the American Society of Dermatopathology Appropriate Use Criteria Committee.

BACKGROUND: Appropriate use criteria (AUC) provide patient-centered physician guidance in test selection. An initial set of AUC was reported by the American Society of Dermatopathology (ASDP) in 2018. AUC reflect evidence collected at single timepoints and may be affected by evolving evidence and experience. The objective of this study was to update and expand AUC for selected tests. METHODS: RAND/UCLA (RAND Corporation [Santa Monica, CA]/University of California Los Angeles) methodology used includes the following: (a) literature review; (b) review of previously rated tests and previously employed clinical scenarios; (c) selection of previously rated tests for new ratings; (d) development of new clinical scenarios; (e) selection of additional tests; (f) three rating rounds with feedback and group discussion after rounds 1 and 2. RESULTS: For 220 clinical scenarios comprising lymphoproliferative (light chain clonality), melanocytic (comparative genomic hybridization, fluorescence in situ hybridization, reverse transcription polymerase chain reaction, telomerase reverse transcriptase promoter), vascular disorders (MYC), and inflammatory dermatoses (periodic acid-Schiff, Gömöri methenamine silver), consensus by panel raters was reached in 172 of 220 (78%) scenarios, with 103 of 148 (70%) rated "usually appropriate" or "rarely appropriate" and 45 of 148 (30%), "appropriateness uncertain." LIMITATIONS: The study design only measures appropriateness. Cost, availability, test comparison, and additional clinical considerations are not measured. The possibility that the findings of this study may be influenced by the inherent biases of the dermatopathologists involved in the study cannot be excluded. CONCLUSIONS: AUC are reported for selected diagnostic tests in clinical scenarios that occur in dermatopathology practice. Adhering to AUC may reduce inappropriate test utilization and improve healthcare delivery.

MYC gene amplification by fluorescence in situ hybridization and MYC protein expression by immunohistochemistry in the diagnosis of cutaneous angiosarcoma: Systematic review and appropriate use criteria.

BACKGROUND: Secondary angiosarcoma (AS) most commonly follows breast cancer and includes postirradiation AS (PRAS) and lymphedema-associated AS. The frequent amplification of MYC (8q24.21) in secondary AS and the rising incidence of PRAS and atypical vascular lesions (AVLs) have prompted interest in the diagnostic and prognostic utility of MYC in AS. METHODS: Retrospective series with ≥2 cases of cutaneous AS and describing the use of fluorescence in situ hybridization (FISH) for MYC amplification or immunohistochemistry (IHC) for MYC overexpression were included. RESULTS: Sixteen studies met inclusion criteria. Overall, 93% of cases evaluated by FISH and IHC were concordant. The sensitivity of FISH in primary AS was only 6.8%, and protein overexpression occurred without amplification in sun-damaged skin. FISH and IHC were over 78% sensitive in secondary AS but negative in over 98% of AVLs. MYC amplification and FLT4 coamplification were associated with shorter overall survival in secondary AS. CONCLUSION: FISH for MYC amplification and IHC for MYC overexpression are useful in distinguishing PRAS from AVLs and may also have prognostic value in secondary AS. In contrast, these methods have little diagnostic or prognostic value in primary AS and should not be used to distinguish primary AS from benign vascular neoplasms.

Clinical, Dermatoscopic, and Histological Findings in a Diagnosis of Pityriasis Lichenoides.

Pityriasis lichenoides et varioliformis acuta (PLEVA) is a rare cutaneous eruption of erythematous macules and papules distributed over the flexural surfaces and the trunk. Histopathologic analysis is useful in diagnosis, and dermoscopic findings have been described in several small case series. We present a case of a mid-20s female who was diagnosed with PLEVA based on clinical and histopathological findings, and we also demonstrate a unique dermoscopic finding. Additionally, we review the current literature detailing dermoscopy findings with associated histopathology in PLEVA and pityriasis lichenoides chronica (PLC).

Disseminated Histoplasmosis Diagnosed by "Touch Prep".

Disseminated histoplasmosis is a rare but serious complication of infection with the dimorphic fungus Histoplasma capsulatum. We report a case of disseminated histoplasmosis with cutaneous involvement diagnosed by touch wet preparation and confirmed with histopathology and culture. "Touch prep" performed from a lesional punch biopsy, prepared with Wright-Giemsa followed by chlorazol black containing KOH, revealed abundant yeast organisms localized within multinucleated giant cells, and a rapid diagnosis of disseminated histoplasmosis with cutaneous involvement was achieved. This report demonstrates the utility of wet prep techniques as an invaluable and rapid beside diagnostic tool in the setting of cutaneous histoplasmosis. In addition, we compare the distinguishing histopathologic features of the infectious organisms within the differential diagnosis of parasitized histiocytes.

Nanoparticle Formulation of Indocyanine Green Improves Image-Guided Surgery in a Murine Model of Breast Cancer.

PURPOSE: Negative surgical margins (NSMs) have favorable prognostic implications in breast tumor resection surgery. Fluorescence image-guided surgery (FIGS) has the ability to delineate surgical margins in real time, potentially improving the completeness of tumor resection. We have recently developed indocyanine green (ICG)-loaded self-assembled hyaluronic acid (HA) nanoparticles (NanoICG) for solid tumor imaging, which were shown to enhance intraoperative contrast. PROCEDURES: This study sought to assess the efficacy of NanoICG on completeness of breast tumor resection and post-surgical survival. BALB/c mice bearing iRFP+/luciferase+ 4T1 syngeneic breast tumors were administered NanoICG or ICG, underwent FIGS, and were compared to bright light surgery (BLS) and sham controls. RESULTS: NanoICG increased the number of complete resections and improved tumor-free survival. This was a product of improved intraoperative contrast enhancement and the identification of a greater number of small, occult lesions than ICG and BLS. Additionally, NanoICG identified chest wall invasion and predicted recurrence in a model of late-stage breast cancer. CONCLUSIONS: NanoICG is an efficacious intraoperative contrast agent and could potentially improve surgical outcomes in breast cancer.

Disseminated Acanthamoeba Infection Presenting With Cutaneous Lesions in an Immunocompromised Patient: A Case Report, Review of Histomorphologic Findings, and Potential Diagnostic Pitfalls.

OBJECTIVES: Free-living amoebas are exceedingly rare causes of cutaneous infections and present unique diagnostic and therapeutic challenges. We describe a case of disseminated acanthamoebiasis with cutaneous manifestations and summarize additional diagnostic, prognostic, and therapeutic highlights. METHODS: A 58-year-old man with relapsed chronic lymphocytic leukemia had several weeks of progressive, painful ulcerations on the forehead, arms, abdomen, and thighs. A biopsy was performed for histopathologic evaluation. RESULTS: The biopsy specimen showed inflammatory infiltrate with abscess formation involving the epidermis, dermis, and subcutis. Scattered cells showed nuclei with a prominent central karyosome, dispersed chromatin, and either abundant foamy basophilic cytoplasm or two well-demarcated cytoplasmic walls. Acanthamoeba species was confirmed by polymerase chain reaction from the formalin-fixed, paraffin-embedded tissue. CONCLUSIONS: Cutaneous lesions from acanthamoebiasis are exceptionally rare but should be included in the differential diagnosis of necrotic cutaneous lesions in immunocompromised patients. Although infrequently encountered, pathologists need to be aware of the morphologic features of free-living amoebas. Immunohistochemical and molecular studies can confirm the diagnosis. Multiagent treatment regimens, when initiated empirically, have been more successful than single-agent regimens, but infections involving the central nervous system are almost universally fatal.

Napsin A expression in small cell carcinoma of the lung: a cytologic study with review of differentials.

INTRODUCTION: Napsin A is a diagnostic marker for pulmonary adenocarcinoma and a useful alternative to thyroid transcription factor 1 (TTF-1). TTF-1 also stains pulmonary small cell carcinoma (SCCA). Napsin A expression in SCCAs is not as established as it is in non-SCCAs. We analyzed napsin A and TTF-1 expression in 36 previously confirmed cytologic cases of pulmonary SCCA. Ours is currently the largest cytologic series of such cases examined for napsin A expression. MATERIALS AND METHODS: Thirty-six patients, (20 men, 16 women), age 43-87 years, mean 57 years, had primary or metastatic pulmonary SCCA diagnosed by fine-needle aspiration biopsies of mediastinum (n = 5); liver (n = 3); subcutaneous nodule (n = 1); lung (n = 6); and axillary, cervical, and mediastinal lymph nodes (n = 20), as well as a pleural effusion (n = 1). Napsin A and TTF-1 expression was tested. Also, previous expression (or lack thereof) with immunocytochemical stains pancytokeratin and neuroendocrine markers (synaptophysin, chromogranin, and cluster of differentiation marker CD56) were noted. RESULTS: All cases of pulmonary SCCA were positive for pancytokeratin. TTF-1 was positive in 35 of 36 cases (97%), and napsin A was negative in all 36 cases (100%). All 36 cases expressed ≥ 1 neuroendocrine marker, including the TTF-1 negative case. CONCLUSIONS: This study showed napsin A was negative in all pulmonary SCCAs. This stain may prove to be a useful exclusionary marker in distinguishing pulmonary SCCA from other poorly differentiated lung carcinomas with similar morphologic features, especially those with concomitant TTF-1 expression.

Epithelioid sarcoma-like (pseudomyogenic) hemangioendothelioma, clinically mimicking dermatofibroma, diagnosed by skin biopsy in a 30-year-old man.

Epithelioid sarcoma-like (pseudomyogenic) hemangioendothelioma (ESHE) represents a rare soft tissue and bone tumor that typically presents as nodule(s) in the distal extremities of young adults. The nodules traverse several tissue planes simultaneously and can involve the dermis, subcutis, skeletal muscle and bone. ESHE shares clinical and microscopic features with epithelioid sarcoma (ES), and, accordingly, is commonly misdiagnosed as ES. However, unlike ES, which has a poor prognosis, ESHE commonly follows an indolent course. Herein, we report a case of ESHE diagnosed by skin biopsy that clinically mimicked a dermatofibroma. We also provide clinical photographs of the lesions in various stages of development, representing information that has not been previously published, to our knowledge.

Chromophobe renal cell carcinoma with sarcomatoid differentiation: a clinicopathologic study of 14 cases.

OBJECTIVE: To investigate the clinicopathologic features of chromophobe renal cell carcinoma with sarcomatoid differentiation. STUDY DESIGN: A search was made through the surgical pathology and expert consult files of two major academic institutions from 2003 to 2011 for cases of chromophobe renal cell carcinoma with sarcomatoid differentiation. RESULTS: Fourteen patients were identified. The patients included 9 males (64%) and 5 females (36%). The mean patient age was 60.4 years (range, 40-82 years). There was a left-sided predominance: left (9 patients) and right (5 patients). The mean tumor size was 14.6 cm (range, 9.5-28.0 cm), and the mean percentage sarcomatoid differentiation was 67% (range, 30-99%). All tumors exhibited moderate to extensive areas of necrosis. The nonsarcomatoid component in all cases demonstrated classic features of chromophobe renal cell carcinoma. Nine patients (64%) had pT3 disease and 5 patients (36%) had pT4 disease. Five patients (36%) had positive surgical margins. Three patients (21%) had tissue diagnosis of metastatic disease at the time of initial surgery. Six patients (43%) had subsequent pathologic and/or radiologic evidence of multiple or isolated metastatic disease. Follow-up information was available in all 14 patients. Mean follow-up time was 16 weeks (range, 2-84 weeks). Ten of 14 patients (71%) died of disease, 9 of those within 6 months (mean survival time of 10 weeks), 3 patients (21%) were alive with disease, and only 1 patient (7%) was alive with no evidence of disease. CONCLUSION: This study is one of the largest series to date specifically examining the clinicopathologic features of sarcomatoid chromophobe renal cell carcinoma in radical nephrectomy specimens and confirms the observation that these tumors behave more aggressively than conventional clear cell renal cell carcinoma or papillary renal cell carcinoma.

Soft tissue chordomas: a clinicopathologic analysis of 11 cases.

Soft tissue chordomas (STCs) have never been systematically studied because of their rarity and the difficulty in separating them from similar-appearing lesions. Using brachyury to confirm the diagnosis, we have analyzed our experience with 11 cases. Cases coded as "chordoma" or "parachordoma" were retrieved from institutional and consultation files (1989 to 2011) and were excluded from further analysis if they arose from the bone or in a patient with previous axial chordoma. Eleven of 27 cases met inclusion criteria. Patients (8 male; 3 female) ranged in age from 13 to 71 years (mean 44 y). Tumors were located on the buttock (n=2), wrist (n=2), leg (n=2), toe (n=1), thumb (n=1), ankle (n=1), shoulder (n=1), and chest wall (n=1), ranged in size from 0.5 to 10.9 cm (mean 5.3 cm), and consisted of cords and syncytia of spindled/epithelioid cells with vacuolated eosinophilic cytoplasm and a partially myxoid background. Tumors expressed brachyury (10/10), 1 or more cytokeratins (11/11), and S100 protein (10/11). Follow-up information was available for 10 patients (69 mo; range, 2 to 212 mo). Most (n=6) were alive without disease, 2 developed local recurrence and lung metastases, and 1 developed lung metastasis only. One died with unknown disease status. STCs are histologically identical to osseous ones, but differ in their greater tendency to occur in distal locations where small size and surgical resectability result in better disease control. The existence of STC implies that notochordal remnants are not a prerequisite for chordoma development.

Deceptively benign low-grade fibromyxoid sarcoma: array-comparative genomic hybridization decodes the diagnosis.

Low-grade fibromyxoid sarcoma (previously known as Evans tumor) is a rare soft tissue neoplasm characterized by a deceptively bland appearance despite the potential for late metastasis or recurrence. We describe a 13-year-old patient with a popliteal fossa mass initially thought to be benign that, because of array-comparative genomic hybridization findings and subsequent immunohistochemistry, was diagnosed as low-grade fibromyxoid sarcoma. The array-comparative genomic hybridization demonstrated a loss of 11p11.2p15.5 and a gain of 16p11.2p13.3 with breakpoints involving the CREB3L1 (cAMP responsive element-binding protein 3-like 1) and FUS (fused in sarcoma) genes, respectively. Subsequent fluorescence in situ hybridization analysis of a dual-labeled break-apart FUS probe on interphase cells was positive. Our case highlights the importance of using genetic information obtained via array-comparative genomic hybridization to classify accurately pediatric soft tissue tumors.

Soft tissue angiofibroma: report of 2 cases of a recently described tumor.

Several soft tissue tumors are characterized by fibrous stroma with a conspicuous vascular component including cellular angiofibroma, nasopharyngeal angiofibroma, and solitary fibrous tumor. Recently, a distinctive fibroblastic tumor composed of bland spindle cells and a complex vascular network has been characterized morphologically and shown to harbor a recurrent t(5;8) translocation with AHRR-NCOA2 gene fusion. We report our recent experience with 2 examples of this benign tumor, the diagnosis for one of which was supported by fluorescence in situ hybridization for NCOA2 rearrangement. Identification of this tumor is important to prevent misdiagnosis as a low-grade sarcoma.

Maturation of intracellular Escherichia coli communities requires SurA.

Escherichia coli is the most common cause of community-acquired urinary tract infection (UTI). During murine cystitis, uropathogenic E. coli (UPEC) utilizes type 1 pili to bind and invade superficial bladder epithelial cells. UPEC then replicates within to form intracellular bacterial communities (IBCs), a process whose genetic determinants are as yet undefined. In this study, we investigated the role of SurA in the UPEC pathogenic cascade. SurA is a periplasmic prolyl isomerase/chaperone that facilitates outer membrane protein biogenesis and pilus assembly in E. coli. Invasion into bladder epithelial cells was disproportionately reduced when surA was genetically disrupted in the UPEC strain UTI89, demonstrating that binding alone is not sufficient for invasion. In a murine cystitis model, UTI89 surA::kan was unable to persist in the urinary tract. Complementation of UTI89 surA::kan with a plasmid (pDH15) containing surA under the control of an arabinose-inducible promoter restored in vivo binding and invasion events. However, the absence of arabinose within the mouse bladder resulted in depletion of SurA after invasion of the bacteria into the superficial epithelial cells. Under these conditions, invasion by UTI89/pDH15 surA::kan was normal, but in contrast to UTI89, UTI89/pDH15 surA::kan formed intracellular collections that contained fewer bacteria, were loosely organized, and lacked the normal transition to a densely packed, coccoid morphology. Our data argue that SurA is required within bladder epithelial cells for UPEC to undergo the morphological changes that underlie IBC maturation and completion of the UTI pathogenic cascade.

Suppression of bladder epithelial cytokine responses by uropathogenic Escherichia coli.

Urinary tract infections are most commonly caused by uropathogenic strains of Escherichia coli (UPEC), which invade superficial bladder epithelial cells via a type 1 pilus-dependent mechanism. Inside these epithelial cells, UPEC organisms multiply to high numbers to form intracellular bacterial communities, allowing them to avoid immune detection. Bladder epithelial cells produce interleukin-6 (IL-6) and IL-8 in response to laboratory strains of E. coli in vitro. We investigated the ability of UPEC to alter epithelial cytokine signaling by examining the in vitro responses of bladder epithelial cell lines to the cystitis strains UTI89 and NU14. The cystitis strains induced significantly less IL-6 than did the laboratory E. coli strain MG1655 from 5637 and T24 bladder epithelial cells. The cystitis strains also suppressed epithelial cytokine responses to exogenous lipopolysaccharide (LPS) and to laboratory E. coli. We found that insertional mutations in the rfa and rfb operons and in the surA gene all abolished the ability of UTI89 to suppress cytokine induction. The rfa and rfb operons encode LPS biosynthetic genes, while surA encodes a periplasmic cis-trans prolyl isomerase important in the biogenesis of outer membrane proteins. We conclude that, in this in vitro model system, cystitis strains of UPEC have genes encoding factors that suppress proinflammatory cytokine production by bladder epithelial cells.