Leslie G. Dodd

Distinct and Overlapping Sarcoma Subtypes Initiated from Muscle Stem and Progenitor Cells

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children, whereas undifferentiated pleomorphic sarcoma (UPS) is one of the most common soft tissue sarcomas diagnosed in adults. To investigate the myogenic cell(s) of origin of these sarcomas, we used Pax7-CreER and MyoD-CreER mice to transform Pax7(+) and MyoD(+) myogenic progenitors by expressing oncogenic Kras(G12D) and deleting Trp53 in vivo. Pax7-CreER mice developed RMS and UPS, whereas MyoD-CreER mice developed UPS. Using gene set enrichment analysis, RMS and UPS each clustered specifically within their human counterparts. These results suggest that RMS and UPS have distinct and overlapping cells of origin within the muscle lineage. Taking them together, we have established mouse models of soft tissue sarcoma from muscle stem and progenitor cells.

Malignancy risk associated with diagnostic categories defined by the Papanicolaou Society of Cytopathology pancreaticobiliary guidelines

Endoscopic ultrasound‐guided fine‐needle aspiration (EUS‐FNA) is currently the predominant method for obtaining a preoperative tissue diagnosis for pancreatic lesions suspicious for malignancy. The diagnostic sensitivity and specificity of EUS‐FNA are well documented, but malignancy risk associated with the diagnostic categories proposed by the Papanicolaou Society of Cytopathology is poorly defined.

FNA smears as a potential source of DNA for targeted next-generation sequencing of lung adenocarcinomas

Diff‐Quik–stained fine‐needle aspiration (FNA) smears and touch preparations from biopsies represent alternative specimens for molecular testing when cell block or biopsy material is insufficient. This study describes the use of these samples for targeted next‐generation sequencing (NGS) of primary and metastatic lung adenocarcinoma and reports the DNA quality and success rates of FNA smears versus other specimens from 1 year of clinical use.

Quantitative Segmentation of Fluorescence Microscopy Images of Heterogeneous Tissue: Application to the Detection of Residual Disease in Tumor Margins

Purpose To develop a robust tool for quantitative in situ pathology that allows visualization of heterogeneous tissue morphology and segmentation and quantification of image features. Materials and Methods Tissue excised from a genetically engineered mouse model of sarcoma was imaged using a subcellular resolution microendoscope after topical application of a fluorescent anatomical contrast agent: acriflavine. An algorithm based on sparse component analysis (SCA) and the circle transform (CT) was developed for image segmentation and quantification of distinct tissue types. The accuracy of our approach was quantified through simulations of tumor and muscle images. Specifically, tumor, muscle, and tumor+muscle tissue images were simulated because these tissue types were most commonly observed in sarcoma margins. Simulations were based on tissue characteristics observed in pathology slides. The potential clinical utility of our approach was evaluated by imaging excised margins and the tumor bed in a cohort of mice after surgical resection of sarcoma. Results Simulation experiments revealed that SCA+CT achieved the lowest errors for larger nuclear sizes and for higher contrast ratios (nuclei intensity/background intensity). For imaging of tumor margins, SCA+CT effectively isolated nuclei from tumor, muscle, adipose, and tumor+muscle tissue types. Differences in density were correctly identified with SCA+CT in a cohort of ex vivo and in vivo images, thus illustrating the diagnostic potential of our approach. Conclusion The combination of a subcellular-resolution microendoscope, acriflavine staining, and SCA+CT can be used to accurately isolate nuclei and quantify their density in anatomical images of heterogeneous tissue.

Use of BRAF v600e immunocytochemistry on FNA direct smears of papillary thyroid carcinoma

Mutations of v‐Raf murine sarcoma viral oncogene homolog B1 (BRAF) are identified in almost half of all papillary thyroid carcinomas (PTCs). These mutations are specific for PTC and may confer a worse prognosis. An immunohistochemical (IHC) stain for BRAF is commercially available and has been validated in surgical specimens. Fine‐needle aspiration (FNA) is frequently used as a diagnostic tool for risk stratification of thyroid nodules. Therefore, the authors evaluated the performance of immunostaining with the anti‐BRAF antibody VE1 on FNA direct smears.

A quantitative microscopic approach to predict local recurrence based on in vivo intraoperative imaging of sarcoma tumor margins

The goal of resection of soft tissue sarcomas located in the extremity is to preserve limb function while completely excising the tumor with a margin of normal tissue. With surgery alone, one‐third of patients with soft tissue sarcoma of the extremity will have local recurrence due to microscopic residual disease in the tumor bed. Currently, a limited number of intraoperative pathology‐based techniques are used to assess margin status; however, few have been widely adopted due to sampling error and time constraints. To aid in intraoperative diagnosis, we developed a quantitative optical microscopy toolbox, which includes acriflavine staining, fluorescence microscopy, and analytic techniques called sparse component analysis and circle transform to yield quantitative diagnosis of tumor margins. A series of variables were quantified from images of resected primary sarcomas and used to optimize a multivariate model. The sensitivity and specificity for differentiating positive from negative ex vivo resected tumor margins was 82 and 75%. The utility of this approach was tested by imaging the in vivo tumor cavities from 34 mice after resection of a sarcoma with local recurrence as a bench mark. When applied prospectively to images from the tumor cavity, the sensitivity and specificity for differentiating local recurrence was 78 and 82%. For comparison, if pathology was used to predict local recurrence in this data set, it would achieve a sensitivity of 29% and a specificity of 71%. These results indicate a robust approach for detecting microscopic residual disease, which is an effective predictor of local recurrence.

Malignancy risk for the categories: Non-diagnostic, benign, atypical, suspicious, and malignant used in the categorization of endobronchial ultrasound guided-fine needle aspirates of pulmonary nodules

Endobronchial ultrasound‐guided fine‐needle aspiration (EBUS‐FNA) is frequently used for the workup of pulmonary nodules. While no universally accepted diagnostic classification exists, many cytopathologists use the categories: Non‐diagnostic, benign, atypical, suspicious and malignant. Sensitivity and specificity for the EBUS technique have been documented, but little information is available for malignancy risk associated with these categories.

Fine-needle-aspiration cytology of a proximal type epithelioid sarcoma: A case report.

Epithelioid sarcoma is a rare mesenchymal neoplasm, with an as yet unidentified cell of origin. Two subtypes of epithelioid sarcoma, distal/classic and proximal/large cell type, are recognized in the literature; with the proximal‐type having a lower incidence amongst the two. Here, we present a case of proximal‐type epithelioid sarcoma in a previously healthy young man. Fine‐needle‐aspiration of a large axillary mass was performed for diagnosis. The cytologic findings included a dispersed population of large epithelioid to polyhedral cells with abundant cytoplasm. Immunohistochemical staining showed coexpression of keratin and vimentin, as well as loss of INI1 staining, consistent with an epithelioid sarcoma, proximal subtype. Diagn. Cytopathol. 2015;43:859–862.

Angiomatoid fibrous histiocytoma: novel MR imaging findings

ObjectiveTo describe novel MR imaging features, and clinical characteristics of soft tissue angiomatoid fibrous histiocytoma (AFH) at presentation, local recurrence, and metastases.Materials and methodsWe described the MRI findings of six cases of histologically proven AFH. Pathologic findings, clinical presentation, and outcome were reviewed.ResultsLesions were primarily cystic. At initial presentation, tumors were surrounded by low signal intensity fibrous pseudocapsule. High signal intensity consistent with the lymphoplasmacytic infiltrate was seen in T2-weighted and post-contrast images as a rim over the hypointense pseudocapsule (double rim sign). High signal intensity infiltrating tumoral cords extended into adjacent tissues, through pseudocapsular defects on T2-weighted and post-contrast images. The cystic component and tumor cell nodularity were demonstrated at post-contrast images. Clinically, lesions were often thought to be benign, underwent marginal resection, developed local recurrence, and one developed second recurrence consisting of metastases. Recurrent tumors appeared as multiple masses, misinterpreted as post-surgical changes. An intramuscular recurrence demonstrated double rim and infiltrating margin.ConclusionsA predominantly well-circumscribed, primarily cystic mass with double-rim and marginal infiltration on MRI suggests the possibility of AFH, in particular in child or young adult. Inclusion of these novel observations in AFH differential diagnosis may have a significant impact on treatment and prevention of recurrence.

Needle biopsy of mesenchymal lesions of the head and neck: Evolving concepts and new strategies for diagnosis

Sarcomas are a rare and heterogeneous group of neoplasms that can be a significant diagnostic challenge in routine practice. Recent advances in the understanding of molecular mechanisms underlying oncogenesis have led to an array of novel diagnostic tools. Here we review several sarcomas of the head and neck region, focusing on neoplasms with new molecular findings and highlighting novel diagnostic tools.