Primary Pulmonary Myxoid Sarcoma and Thoracic Angiomatoid Fibrous Histiocytoma: Two Sides of the Same Coin?

Primary pulmonary myxoid sarcoma (PPMS) and thoracic angiomatoid fibrous histiocytoma (AFH) are rare neoplasms with EWSR1 fusions and overlapping morphology. Both tumor types often show epithelial membrane antigen expression, but AFH characteristically co-expresses desmin. We encountered a case of PPMS with the unexpected finding of patchy, strong anaplastic lymphoma kinase (ALK) (previously reported in AFH) and synaptophysin expression. We evaluated a cohort of PPMS and thoracic AFH with systematic morphologic comparison and surveyed for aberrant expression of ALK and synaptophysin. Medical records and slides were reviewed for 16 molecularly confirmed cases of PPMS (n=5) and thoracic AFH (n=11). Each case was scored for morphologic characteristics typical of PPMS and/or AFH. ALK, synaptophysin, chromogranin, desmin, and epithelial membrane antigen immunostains were performed on cases with available tissue. AFH and PPMS cases showed similar age at presentation and long-term tumor behavior. Almost all cases of PPMS and AFH had a fibrous pseudocapsule and lymphoid rim. All PPMS had myxoid stroma and reticular growth pattern, but these features were also present in a subset of AFH. Synaptophysin expression was present in 6 of 11 AFH and 1 of 5 PPMS; all tested cases were negative for chromogranin (n=15). One case of AFH and 1 case of PPMS showed focally strong coexpression of synaptophysin and ALK. AFH and PPMS show considerable clinicopathologic overlap. When supportive, the immunohistochemical findings described may aid in diagnosis before molecular confirmation. PPMS and AFH may be morphologic variants of the same clinicopathologic entity, which can show more immunophenotypic variability than previously reported.

Sarcomas Harboring EWSR1::PATZ1 Fusions: A Clinicopathologic Study of 17 Cases

Soft tissue sarcomas harboring EWSR1::PATZ1 are a recently recognized entity with variable morphology and a heterogeneous immunohistochemical profile. We studied 17 such tumors. The tumors occurred in 12 men and 5 women (median age, 50 years; range, 15-71 years), involved the thoracoabdominal soft tissues (14 cases; 82%), lower extremities (2 cases; 12%), and tongue (1 case; 6%), and ranged from 0.7 to 11.3 cm (median, 4.7 cm). All but 1 patient received complete surgical resection; 7 were also treated with neoadjuvant chemo/radiotherapy. All cases showed typical features of EWSR1::PATZ1 sarcoma, including uniform round to spindled cells, fibromyxoid matrix, fibrous bands, hyalinized vessels, and pseudoalveolar/microcystic spaces. Unusual features, seen in a subset of cases, included degenerative-appearing nuclear atypia, epithelioid cytomorphology, mature fat, abundant rhabdomyoblasts, high mitotic activity, and foci with increased cellularity and nuclear atypia. Positive immunohistochemical results were desmin (16/17, 94%), MyoD1 (13/14, 93%), myogenin (6/14, 43%), GFAP (10/10, 100%), S100 protein (15/17, 88%), SOX10 (7/13, 54%), keratin (10/17, 59%), CD99 (4/11, 36%), H3K27me3 (retained expression 9/9, 100%), p16 (absent expression 1/4, 25%), and p53 (wild type 3/3, 100%). Fusion events included EWSR1 exon 8::PATZ1 exon 1 (14/17, 82%), EWSR1 exon 9::PATZ1 exon 1 (2/17, 12%), and EWSR1 exon 7::PATZ1 exon 1 (1/17, 6%). No evaluated tumor had alterations of CDKN2A/B and/or TP53, or MDM2 amplification. Clinical follow-up (16 patients: median, 13.5 months; range, 1-77 months) showed distant metastases in 3 patients (1/3 at time of presentation) and no local recurrences. At the time of last follow-up, 14 patients were disease free, 1 was alive with disease, 1 was dead of disease (at 13 months), and 1 had an indeterminant pulmonary nodule. We conclude that the morphologic spectrum of EWSR1::PATZ1 is broader than has been previously appreciated. Although more long-term follow-up is needed, the prognosis of these very rare sarcomas may be more favorable than previously reported.

EWSR1::POU2AF3(COLCA2) Sarcoma: An Aggressive, Polyphenotypic Sarcoma With a Head and Neck Predilection

EWSR1::POU2AF3 (COLCA2) sarcomas are a recently identified group of undifferentiated round/spindle cell neoplasms with a predilection for the head and neck region. Herein, we report our experience with 8 cases, occurring in 5 men and 3 women (age range, 37-74 years; median, 60 years). Tumors involved the head/neck (4 cases), and one each the thigh, thoracic wall, fibula, and lung. Seven patients received multimodal therapy; 1 patient was treated only with surgery. Clinical follow-up (8 patients; range, 4-122 months; median, 32 months) showed 5 patients with metastases (often multifocal, with a latency ranging from 7 to 119 months), and 3 of them also with local recurrence. The median local recurrence-free and metastasis-free survival rates were 24 months and 29 months, respectively. Of the 8 patients, 1 died of an unknown cause, 4 were alive with metastatic disease, 1 was alive with unresectable local disease, and 2 were without disease. The tumors were composed of 2 morphologic subgroups: (1) relatively bland tumors consisting of spindled to stellate cells with varying cellularity and fibromyxoid stroma (2 cases) and (2) overtly malignant tumors composed of nests of "neuroendocrine-appearing" round cells surrounded by spindled cells (6 cases). Individual cases in the second group showed glandular, osteogenic, or rhabdomyoblastic differentiation. Immunohistochemical results included CD56 (4/4 cases), GFAP (5/8), SATB2 (4/6), keratin (AE1/AE3) (5/8), and S100 protein (4/7). RNA sequencing identified EWSR1::POU2AF3 gene fusion in all cases. EWSR1 gene rearrangement was confirmed by fluorescence in situ hybridization in 5 cases. Our findings confirm the head/neck predilection and aggressive clinical behavior of EWSR1::POU2AF3 sarcomas and widen the morphologic spectrum of these rare lesions to include relatively bland spindle cell tumors and tumors with divergent differentiation.

Non-cutaneous syncytial myoepitheliomas are identical to cutaneous counterparts: a clinicopathologic study of 24 tumors occurring at diverse locations

AIMS

Cutaneous syncytial myoepithelioma (CSM) is a rare myoepithelioma variant of skin, characterized by intradermal syncytial growth of spindle cells with a distinct immunophenotype of EMA and S100 positivity and infrequent keratin expression. While CSM was first described as a cutaneous tumor, singular non-cutaneous cases have since been reported in bone. We aimed to investigate the clinicopathological features of this variant across all anatomic sites through a large multi-institutional study.

METHODS AND RESULTS

We complied a total of 24 myoepitheliomas with syncytial growth from our files. The tumors occurred in 12 male and 12 female patients (M:F = 1:1), with a median age of 31 years (range, 9-69 years). While the majority of tumors (75%, n = 18) occurred in skin, a significant subset (25%, n = 6) arose in non-cutaneous sites, including bone (n = 3), bronchus/trachea (n = 2), and interosseous membrane of tibia/fibula (n = 1). Tumor size ranged from 0.4 to 5.9 cm. Clinical follow-up (7 patients; range 14-202 months; median 56.5 months) showed a single local recurrence 8 years after incomplete skin excision but no metastases; all patients were alive at the time of last follow-up without evidence of disease. Histologically, all tumors were pink at low-power and characterized by a syncytial growth of bland ovoid, spindled, or histiocytoid cells with eosinophilic cytoplasm and prominent perivascular lymphoplasmacytic inflammation. One-third displayed adipocytic metaplasia (8/24). Rare cytologic atypia was seen but was not associated with increased mitotic activity. All tumors expressed S100, SMA, and/or EMA. Keratin expression was absent in most cases. Molecular analysis was performed in 16 cases, all showing EWSR1-rearrangments. In total, 15/15 (100%) harbored an EWSR1::PBX3 fusion, whereas 1 case EWSR1 FISH was the only molecular study performed.

CONCLUSION

Syncytial myoepithelioma is a rare but recognizable morphologic variant of myoepithelioma which may have a predilection for skin but also occurs in diverse non-cutaneous sites. Our series provides evidence supporting a reappraisal of the term "cutaneous syncytial myoepithelioma," as 25% of patients in our series presented with non-cutaneous tumors; thus, we propose the term "syncytial myoepithelioma" to aid pathologist recognition and avoidance of potentially confusing terminology when referring to non-cutaneous examples. The behavior of syncytial myoepithelioma, whether it arises in cutaneous or non-cutaneous sites, is indolent and perhaps benign with a small capacity for local recurrence.

Lipoblastoma-Like Tumor and Fibrosarcoma-Like Lipomatous Neoplasm Represent the Same Entity: A Clinicopathologic and Molecular Genetic Study of 23 Cases Occurring in Both Men and Women at Diverse Locations

Lipoblastoma-like tumor (LLT) is a benign soft tissue tumor demonstrating mixed morphologic features of lipoblastoma, myxoid liposarcoma, and spindle cell lipoma but lacking genetic alterations associated with those tumors. LLT was originally thought to be specific to the vulva but has since been reported in the paratesticular region. The morphologic features of LLT overlap with those of "fibrosarcoma-like lipomatous neoplasm" (FLLN), a rare, indolent adipocytic neoplasm considered by some to form part of the spectrum of atypical spindle cell and pleomorphic lipomatous tumor. We compared the morphologic, immunohistochemical, and genetic features of 23 tumors previously classified as LLT (n = 17) and FLLN (n = 6). The 23 tumors occurred in 13 women and 10 men (mean age, 42 years; range, 17 to 80 years). Eighteen (78%) cases arose in the inguinogenital region, whereas 5 tumors (22%) involved noninguinogenital soft tissue, including the flank (n = 1), shoulder (n = 1), foot (n = 1), forearm (n = 1), and chest wall (n = 1). Microscopically, the tumors were lobulated and septated, with variably collagenized fibromyxoid stroma, prominent thin-walled vessels, scattered univacuolated or bivacuolated lipoblasts, and a minor component of mature adipose tissue. Using immunohistochemistry, 5 tumors (42%) showed complete RB1 loss, with partial loss in 7 cases (58%). RNA sequencing, chromosomal microarray, and DNA next-generation sequencing study results were negative for significant alterations. There were no clinical, morphologic, immunohistochemical, or molecular genetic differences between cases previously classified as LLT or FLLN. Clinical follow-up (11 patients [48%]; range, 2-276 months; mean, 48.2 months) showed all patients were alive without disease, and only one patient had experienced a single local recurrence. We conclude that LLT and FLLN represent the same entity, for which "LLT" seems most appropriate. LLT may occur in either sex and any superficial soft tissue location. Careful morphologic study and appropriate ancillary testing should allow for the distinction of LLT from its potential mimics.

Perineurioma of the sciatic nerve with reticular, microcystic, and pseudolipoblastic features: illustrative case

BACKGROUND

Perineuriomas are peripheral nerve sheath tumors that are composed of benign, localized proliferations of perineural cells and further subclassified as intraneural or extraneural (soft tissue) based on their relationship to the histological boundaries of the nerve. Multiple histological variants have been described, and herein the authors present the first known case of a pseudolipoblastic perineurioma affecting the nerve.

OBSERVATIONS

A 52-year-old woman presented with a 5-year history of progressive, severe left buttock pain radiating down to the top of her foot and ankle, without any associated weakness, with a large mass in her sciatic nerve noted on magnetic resonance imaging (MRI). She underwent resection, which demonstrated a pseudolipoblastic perineurioma of the sciatic nerve, an unusual histological subtype composed of perineurial cells with an abundant clear intracytoplasmic background. Postoperatively, her pain resolved, and follow-up MRI showed no tumor persistence or recurrence.

LESSONS

On imaging, this lesion had a benign appearance, with areas suggestive of subacute hemorrhage, and was associated with a nerve. Although the distinctive morphological features of this lesion may suggest liposarcoma, careful morphological evaluation and appropriate immunohistochemical studies allow its correct classification.

Angiosarcoma arising in a schwannoma of the peripheral nervous system: illustrative case

BACKGROUND

Schwannomas of the peripheral nerves are benign tumors that can very rarely undergo malignant transformation. These lesions are particularly challenging to diagnose via noninvasive techniques but can have significant implications for treatment.

OBSERVATIONS

This is a case of a 70-year-old female with a prior history of a right sciatic notch tumor that was diagnosed as a conventional schwannoma via histology from an initial biopsy and subsequent surgical debulking. Unfortunately, she experienced significant worsening of her motor deficit, whereby her postoperative foot weakness progressed to complete foot drop in less than 2 years. In addition, she demonstrated significant radiological progression, with more than 1 to 2 cm of growth in each dimension at her subsequent evaluation, along with intractable right leg pain. An additional operation was performed to completely remove the 7 × 8 cm tumor, and histology demonstrated angiosarcoma within a schwannoma. There was no evidence of recurrence at 15 months, and the patient had significant improvement in her pain.

LESSONS

Rapidly worsening function and radiological progression are not typically seen with conventional benign nerve sheath tumors and should prompt consideration of other lesions. Angiosarcoma within schwannoma is a rare pathology and optimal therapies for these tumors in terms of surgical timing and adjuvant therapy are still unknown.

Vulvar glomangioma: A case report and literature review

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Vulvar glomangioma is a rare cause of pelvic pain and can be confused with angiomyxoma or Bartholin gland cyst.

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Vulvar glomangioma are best treated with resection.

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Glomangiomas are associated with GLMN gene mutations.

GLMN is a gene that encodes a critical protein necessary for normal vascular development. Mutations of GLMN predispose individuals to development of glomangiomas, with nearly 100% penetrance by age 30. Glomangiomas are tumors of the glomus body, a thermoregulatory arterial-venous shunt composed of modified smooth muscle cells. Vulvar glomangioma is an exceedingly rare cause of chronic pelvic pain, that may be easily confused for other conditions such as Bartholin’s gland abscess or deep angiomxyomas, thereby delaying diagnosis and treatment. Glomangiomas have characteristic pathologic and imaging findings which may aid diagnosis. We herein describe the case of a 24-year-old female who developed chronic pelvic pain in the setting of a vulvar glomangioma. We further delineate the magnetic resonance imaging and biopsy findings critical to her diagnosis, and the appropriate steps taken for surgical management. She was found to harbor a heterozygous GLMN mutation. To the best of our knowledge, this is the first description of such a case in the medical literature.

Malignant rhabdoid tumor: Cyto-histologic correlation and immunohistochemical characterization of a rare pediatric malignancy and its differential diagnoses

Malignant rhabdoid tumor of the kidney (MRTK) is a rare aggressive pediatric renal tumor which can be diagnosed via fine-needle aspiration (FNA) cytology and core biopsy. The diagnosis of MRTK is challenging, and requires morphologic, immunohistochemical and clinical correlation to distinguish it from other entities. The differential diagnosis includes Wilms tumor, desmoplastic small round cell tumor, rhabdomyosarcoma, synovial sarcoma, renal medullary carcinoma, and epithelioid sarcoma. Here we describe a case of MRTK diagnosed on renal cytology and core biopsy with immunohistochemistry and follow by nephrectomy with gross and morphologic findings.

NUTM1-rearranged colorectal sarcoma: a clinicopathologically and genetically distinctive malignant neoplasm with a poor prognosis

NUTM1 gene rearrangements were originally identified in NUT carcinoma. Recently, NUTM1 has been discovered to rearrange with a variety of gene partners in malignancies of diverse location and type. Only one NUTM1-rearranged tumor occurring in the colon has been reported. Herein we report five such tumors. The five tumors occurred in four females and one male, ranging from 38 to 67 years of age (median 51 years). The masses occurred in the colon (cecum, descending, sigmoid) and ileocecal valve region, measuring 2.5-20 cm in size (median 7 cm). Four patients had metastases at presentation (liver, n = 4; lymph nodes, n = 3). Histologically, the lesions arose in the submucosa, infiltrating into the mucosa and muscularis propria, and grew in fibrosarcoma-like fascicles and sheets of epithelioid or rhabdoid cells, with foci of hyalinized to vaguely osteoid-like matrix. The tumors were composed of relatively monomorphic, spindled to epithelioid cells with focal rhabdoid morphology, hyperchromatic nuclei, and small nucleoli. Mitotic activity was usually low (range 1-14/10 HPF; median 5/10 HPF); necrosis was present in two cases. Variable keratin expression and uniform nuclear NUT expression was present; KIT/DOG1 were negative and SMARCB1/SMARCA4 were retained. Next-generation sequencing identified MXD4-NUTM1 rearrangement in all cases (breakpoints: MXD4 exon 5, NUTM1 exons 2 or 3). Follow-up showed one of the four patients who presented with metastases to be dead of disease at 30 months; the other three patients were alive with metastatic disease. The final patient is disease-free, 5 months after diagnosis. NUTM1-rearranged colorectal sarcomas have characteristic morphologic, immunohistochemical, and molecular genetic features, suggesting that they represent a distinct entity within the family of NUTM1-rearranged neoplasia. A NUTM1-rearranged tumor should be considered for any difficult-to-classify submucosal spindle cell neoplasm of the gastrointestinal tract, in particular keratin-positive tumors showing an unusual combination of fibrosarcomatous, epithelioid to rhabdoid and hyalinized morphologies. Recognition of MXD4-NUTM1 rearranged sarcomas may be therapeutically important, even though best treatment is currently elusive/unknown.

GAS7 Deficiency Promotes Metastasis in MYCN-Driven Neuroblastoma

One of the greatest barriers to curative treatment of neuroblastoma is its frequent metastatic outgrowth prior to diagnosis, especially in cases driven by amplification of the MYCN oncogene. However, only a limited number of regulatory proteins that contribute to this complex MYCN-mediated process have been elucidated. Here we show that the growth arrest-specific 7 (GAS7) gene, located at chromosome band 17p13.1, is preferentially deleted in high-risk MYCN-driven neuroblastoma. GAS7 expression was also suppressed in MYCN-amplified neuroblastoma lacking 17p deletion. GAS7 deficiency led to accelerated metastasis in both zebrafish and mammalian models of neuroblastoma with overexpression or amplification of MYCN. Analysis of expression profiles and the ultrastructure of zebrafish neuroblastoma tumors with MYCN overexpression identified that GAS7 deficiency led to (i) downregulation of genes involved in cell-cell interaction, (ii) loss of contact among tumor cells as critical determinants of accelerated metastasis, and (iii) increased levels of MYCN protein. These results provide the first genetic evidence that GAS7 depletion is a critical early step in the cascade of events culminating in neuroblastoma metastasis in the context of MYCN overexpression. SIGNIFICANCE: Heterozygous deletion or MYCN-mediated repression of GAS7 in neuroblastoma releases an important brake on tumor cell dispersion and migration to distant sites, providing a novel mechanism underlying tumor metastasis in MYCN-driven neuroblastoma.See related commentary by Menard, p. 2815.

Clinicopathological, immunophenotypic and genetic studies of mediastinal paragangliomas†

OBJECTIVES

Paragangliomas have unique features in the mediastinum, in part due to their location. Because of their paucity, they have not been thoroughly investigated. We studied the clinical, pathological, immunohistochemical and molecular features of mediastinal paragangliomas.

METHODS

Immunohistochemistry, next-generation sequencing mutation panel and the Oncoscan assay were performed.

RESULTS

Twenty-four patients with mediastinal paraganglioma (7 men, 29.2%) had a median age of 45.5 years (19.8-72.2). Twenty-one (87.5%) paragangliomas were completely resected. Six (of 24, 25.0%) tumours were considered metastatic. Mitotic activity occurred in 11 (of 24, 45.8%) paragangliomas. Programmed death-ligand 1 (PD-L1) (n = 23) was expressed in 6 (26%) patients in 10% (n = 2) and 1% (n = 4) of tumour cells, respectively. SDHB expression was lost in 19 (of 22, 86.4%) cases. ATRX expression was lost in 11 (of 23, 47.8%) cases. Next-generation sequencing revealed a single pathogenic mutation in 10 (of 19) specimens including SDHB (n = 4), SDHD (n = 6), SDHC (n = 1), ATRX (n = 1), and ≥2 mutations in 2 cases [SDHC and TERT (n = 1); SDHB, ATRX and TP53 (n = 1)]. Germline mutation analysis revealed the same succinate dehydrogenase mutation (or lack thereof) as identified in the paraganglioma in 11 (of 12) cases. During a median follow-up (n = 21) of 4.8 years (0.8-14.9), 3 patients developed metastases; 4 patients died, at least 1 of disease.

CONCLUSIONS

Mediastinal paragangliomas can be associated with morbidity and mortality. Many mediastinal paragangliomas have been reported to be associated with syndromes such as multiple endocrine neoplasia, von Hippel-Lindau or succinate dehydrogenase syndrome with mutation profiles dominated by alterations in genes associated with these syndromes.

MyoD1 expression in fibroepithelial stromal polyps

Fibroepithelial stromal polyps (FESPs) are benign polypoid mesenchymal lesions thought to arise from desmin-positive specialized stromal cells of the female genital tract. Although most cases are easily diagnosed by morphology alone, the morphology of FESPs is variable and in some instances can contain hypercellular stroma with numerous atypical desmin-positive cells, simulating botryoid embryonal rhabdomyosarcoma (ERMS). Recently, we encountered a cellular FESP showing desmin expression as well as nuclear immunoreactivity for the skeletal muscle-associated transcription factor MyoD1. Although these lesions are widely known to express desmin, there are very few studies examining expression of the more specific markers of skeletal muscle differentiation, myogenin and MyoD1. The aim of our study was to examine desmin, MyoD1, and myogenin expression in a series of 25 FESPs. Of the 25 cases, desmin expression was present in 23 (92%), at least focal MyoD1 expression was present in 10 (40%), and all cases were negative for myogenin. Follow-up data were available for all 25 cases, and none recurred or behaved in a malignant fashion. Awareness of this potential immunohistochemical pitfall and careful morphologic evaluation should allow for the confident distinction of MyoD1-positive FESP from botyroid ERMS in almost all instances.

Radiologic-Pathologic Correlation: Acellular Dermal Matrix (Alloderm®) Used in Breast Reconstructive Surgery

Acellular dermal matrix (ADM) such as Alloderm^® is sometimes used in tissue reconstruction in primary and reconstructive breast surgeries. As ADM is incorporated into the native tissues, the evolving imaging findings that would correlate with varying degrees of host migration and neoangiogenesis into the matrix can be challenging to recognize. In the setting of a palpable or clinical area of concern after breast reconstructive surgery following breast cancer, confident diagnosis of a mass representing ADM rather than recurring or developing disease can be challenging. Such diagnostic imaging uncertainties generally result in short-term imaging and clinical follow-up, but occasionally, biopsy is performed for histopathological confirmation of benignity. A case of biopsy-proven Alloderm^® is described. To the best of our knowledge, this is the first radiologic-pathologic correlation of ADM in the literature.

Hypoxia-related microRNA-210 is a diagnostic marker for discriminating osteoblastoma and osteosarcoma

Osteoblastoma is a benign bone tumor that can often be difficult to distinguish from malignant osteosarcoma. Because misdiagnosis can result in unfavorable clinical outcomes, we have investigated microRNAs as potential diagnostic biomarkers for distinguishing between these two tumor types. Next generation RNA sequencing was used as an expression screen to evaluate >2,000 microRNAs present in tissue derived from rare formalin fixed paraffin embedded (FFPE) archival tumor specimens. MicroRNAs displaying the greatest ability to discriminate between these two tumors were validated on an independent tumor set, using qPCR assays. Initial screening by RNA-seq identified four microRNA biomarker candidates. Expression of three miRNAs (miR-451a, miR-144-3p, miR-486-5p) was higher in osteoblastoma, while the miR-210 was elevated in osteosarcoma. Validation of these microRNAs on an independent data set of 22 tumor specimens by qPCR revealed that miR-210 is the most discriminating marker. This microRNA displays low levels of expression across all of the osteoblastoma specimens and robust expression in the majority of the osteosarcoma specimens. Application of these biomarkers to a clinical test case showed that these microRNA biomarkers permit re-classification of a misdiagnosed FFPE tumor sample from osteoblastoma to osteosarcoma. Our findings establish that the hypoxia-related miR-210 is a discriminatory marker that distinguishes between osteoblastoma and osteosarcoma. This discovery provides a complementary molecular approach to support pathological classification of two diagnostically challenging musculoskeletal tumors. Because miR-210 is linked to the cellular hypoxia response, its detection may be linked to well-established pro-angiogenic and metastatic roles of hypoxia in osteosarcomas and other tumor cell types. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1137-1146, 2017.

Pseudolipoblastic perineurioma: an unusual morphological variant of perineurioma that may simulate liposarcoma

Perineuriomas are rare peripheral nerve sheath tumors arising from or differentiating along the lines of normal perineurial cells. They can be divided into intraneural and soft tissue types, with the latter category including a significant number of morphological variants. Herein, we further expand their morphological spectrum to include "pseudolipoblastic" perineuriomas. These lesions occurred in the tongue of a 30-year-old man and in the triceps of a 67-year-old woman and were characterized by bland, epithelioid cells with striking intracytoplasmic vacuolization. The architecture varied, with some areas showing a striking "net-like" or "microreticular" pattern and smaller areas having a more typical spindled and whorled appearance. Clinical follow-up (5months and 52months, respectively) showed no evidence of local recurrence or metastasis. Multiple perineurial markers, including epithelial membrane antigen, claudin-1, GLUT-1, and collagen IV, were diffusely positive. Both cases were submitted in consultation out of concern that they represented high-grade liposarcomas. To the best of our knowledge, this unusual morphological variant of perineurioma has not been reported. These tumors appear to be entirely benign and should be cured with simple excision. Pseudolipoblastic perineuriomas should be distinguished from round cell and epithelioid pleomorphic liposarcomas, as well as from other tumors that may show prominent intracytoplasmic vacuolization.

RNA sequencing reveals a depletion of collagen targeting microRNAs in Dupuytren's disease

Background

Dupuytren’s disease is an inherited disorder in which patients develop fibrotic contractures of the hand. Current treatment strategies include surgical excision or enzymatic digestion of fibrotic tissue. MicroRNAs, which are key posttranscriptional regulators of genes expression, have been shown to play an important regulatory role in disorders of fibrosis. Therefore in this investigation, we apply high throughput next generation RNA sequencing strategies to characterize microRNA expression in diseased and healthy palmar fascia to elucidate molecular mechanisms responsible for pathogenic fibrosis.

Methods

We applied high throughput RNA sequencing techniques to quantify the expression of all known human microRNAs in Dupuytren’s and control palmar fascia. MicroRNAs that were differentially expressed between diseased and healthy tissue samples were used for computational target prediction using the bioinformatics tool ComiR. Molecular pathways that were predicted to be differentially expressed based on computational analysis were validated by performing RT-qPCR on RNA extracted from diseased and non-diseased palmar fascia biopsies.

Results

A comparison of microRNAs expressed in Dupuytren’s fascia and control fascia identified 74 microRNAs with a 2-fold enrichment in Dupuytren’s tissue, and 32 microRNAs with enrichment in control fascia. Computational target prediction for differentially expressed microRNAs indicated preferential targeting of collagens and extracellular matrix related proteins in control palmar fascia. RT-qPCR confirmed the decreased expression of microRNA targeted collagens in control palmar fascia tissues.

Discussion

Control palmar fascia show decreased expression of mRNAs encoding collagens that are preferentially targeted by microRNAs enriched in non-diseased fascia. Thus alterations in microRNA regulatory networks may play an important role in driving the pathogenic fibrosis seen in Dupuytren’s disease via direct regulatory effects on extracellular matrix protein synthesis.

Conclusion

Dupuytren’s fascia and healthy palmar fascia can be distinguished by unique microRNA profiles, which are predicted to preferentially target collagens and other extracellular matrix proteins.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-015-0135-8) contains supplementary material, which is available to authorized users.

Intramuscular hemangioma of the scalene musculature masquerading as a paraganglioma: a case series

Intramuscular hemangiomas (IMHs) are uncommon benign vascular lesions, which develop in skeletal muscle. Herein, two cases of IMHs involving the cervical scalene musculature are presented. Such lesions are exceedingly rare, and can be difficult to distinguish from vagal paragangliomas based on clinical presentation, exam, and radiography. Complete surgical excision is the treatment of choice, and was successful in our two index patients. While rare, IMHs of the scalene muscles should be considered in the differential diagnosis of deep neck space masses.

Biomarker-based prediction of response to therapy for colorectal cancer: current perspective

The diagnosis and management of colorectal cancer (CRC) has been impacted by the discovery and validation of a wide variety of biomarkers designed to facilitate a personalized approach for the treatment of the disease. Recently, CRC has been reclassified based on molecular analyses of various genes and proteins capable of separating morphologic types of tumors into molecular categories. At the same time, a number of new prognostic and predictive single genes and proteins have been discovered that are designed to reflect sensitivity and/or resistance to existing therapies. Multigene predictors have also been developed to predict the risk of relapse for intermediate-stage CRC after completion of surgical extirpation. More recently, a number of biomarkers tested by a variety of methods have been proposed as specific predictors of chemotherapy and radiotherapy response. Other markers have been successfully used to predict toxic effects of standard therapies. In this review, a series of novel biomarkers are considered and compared with standard-of-care markers for their potential use as pharmacogenomic and pharmacogenetic predictors of disease outcome.