Inga-Marie Schaefer

Aberrant DNA hypermethylation of SDHC: a novel mechanism of tumor development in Carney triad

Carney triad (CT) is a rare condition with synchronous or metachronous occurrence of gastrointestinal stromal tumors (GISTs), paragangliomas (PGLs), and pulmonary chondromas in a patient. In contrast to Carney-Stratakis syndrome (CSS) and familial PGL syndromes, no germline or somatic mutations in the succinate dehydrogenase (SDH) complex subunits A, B, C, or D have been found in most tumors and/or patients with CT. Nonetheless, the tumors arising among patients with CT, CSS, or familial PGL share a similar morphology with loss of the SDHB subunit on the protein level. For the current study, we employed massive parallel bisulfite sequencing to evaluate DNA methylation patterns in CpG islands in proximity to the gene loci of all four SDH subunits. For the first time, we report on a recurrent aberrant dense DNA methylation at the gene locus of SDHC in tumors of patients with CT, which was not present in tumors of patients with CSS or PGL, or in sporadic GISTs with KIT mutations. This DNA methylation pattern was correlated to a reduced mRNA expression of SDHC, and concurrent loss of the SDHC subunit on the protein level. Collectively, these data suggest epigenetic inactivation of the SDHC gene locus with functional impairment of the SDH complex as a plausible alternate mechanism of tumorigenesis in CT.

Loss of H3K27 trimethylation distinguishes malignant peripheral nerve sheath tumors from histologic mimics.

The diagnosis of malignant peripheral nerve sheath tumor is challenging, particularly in the sporadic setting. Inactivation of the polycomb repressive complex 2 (PRC2), resulting from inactivating mutations of its constituents SUZ12 or EED1, has recently been identified in 70–90% of malignant peripheral nerve sheath tumors. Homozygous PRC2 inactivation results in loss of histone H3K27 trimethylation (H3K27me3). PRC2 inactivation promotes tumor progression and may render patients sensitive to epigenetic-based targeted therapies. H3K27me3 loss has not yet been validated as a diagnostic marker. We evaluated immunohistochemistry for H3K27me3 in 100 malignant peripheral nerve sheath tumors (70 sporadic, 10 neurofibromatosis type 1-associated, 10 radiation-associated, 10 epithelioid) and 200 other spindle cell neoplasms representing potential mimics (20 each monophasic synovial sarcoma, leiomyosarcoma, dedifferentiated liposarcoma, malignant solitary fibrous tumor, low-grade fibromyxoid sarcoma, cellular schwannoma, spindle cell melanoma, unclassified postradiation sarcoma; 10 each atypical neurofibroma, spindle cell rhabdomyosarcoma, gastrointestinal stromal tumor, fibrosarcomatous dermatofibrosarcoma protuberans). In total, 51 (51%) malignant peripheral nerve sheath tumors, including 34 (49%) sporadic, 7 (70%) neurofibromatosis type 1-associated, and 10 (100%) radiation-associated, but no epithelioid malignant peripheral nerve sheath tumors, were negative for H3K27me3. An additional 6 (6%) tumors showed heterogeneous H3K27me3 expression. Among the 90 sporadic, neurofibromatosis type 1-associated, and radiation-associated malignant peripheral nerve sheath tumors, complete H3K27me3 loss was observed in 29% of low-grade, 59% of intermediate-grade, and 83% of high-grade tumors (low vs intermediate/high grade, P=0.0003). Among other tumor types, 4 (20%) unclassified postradiation sarcomas were negative for H3K27me3, whereas all other neoplasms were positive. Loss of H3K27me3 is highly specific for malignant peripheral nerve sheath tumor (although only modestly more sensitive than S-100 protein and SOX10) and may be a useful diagnostic marker. Our findings suggest that PRC2 inactivation in malignant peripheral nerve sheath tumor may occur during progression to higher grades.

Prevalence and risk factors of actinic keratoses in Germany--analysis of multisource data.

In Europe, only few and inconsistent data on the prevalence and treatment of actinic keratoses (AK) are available.

Gastrointestinal stromal tumors

IntroductionThe gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the intestinal tract, known to be refractory to conventional chemotherapy or radiation. Its pathogenesis is defined by mutations within the KIT and PDGFRA gene, which constitutively activate KIT and PDGFRA oncoproteins, and serve as crucial diagnostic and therapeutic targets.DiscussionBesides surgery, therapy with imatinib mesylate, which inhibits KIT kinase activity, represents the other cornerstone for the treatment of GIST. Still, the only curative option for GIST is given after complete surgical removal even in a metastatic setting, but recurrence is common, and the risk can be defined by surgical factors like incomplete resection, intraperitoneal rupture, or bleeding and tumor associated factors like tumor size, mitotic index, or localization.ConclusionConsequently, adjuvant therapy with imatinib mesylate or other tyrosine kinase inhibitors is recommended for high-risk patients after complete resection. For unresectable and advanced GIST, a partial response or stable disease can be achieved in about 80% of patients with imatinib mesylate.

Pancreatic undifferentiated rhabdoid carcinoma: KRAS alterations and SMARCB1 expression status define two subtypes

Pancreatic undifferentiated carcinoma is a heterogeneous group of neoplasms, including pleomorphic giant cell, sarcomatoid, round cell, and rhabdoid carcinomas, the molecular profiles of which have so far been insufficiently characterized. We studied 14 undifferentiated carcinomas with prominent rhabdoid cells, occurring as advanced tumors in seven females and seven males aged 44–96 years (mean: 65 years). Histologically, 10 tumors qualified as pleomorphic giant cell and 4 as monomorphic anaplastic carcinomas. A glandular component, either in the primary or in the metastases, was seen in 5 out of 14 tumors (4 out of 10 pleomorphic giant cell and 1 out of 4 monomorphic anaplastic subtypes, respectively). Osteoclast-like giant cells were absent. Immunohistochemistry revealed coexpression of cytokeratin and vimentin, and loss of membranous β-catenin and E-cadherin staining in the majority of cases. Nuclear SMARCB1 (INI1) expression was lost in 4 out of 14 cases (28%), representing all 4 tumors of the monomorphic anaplastic subtype. FISH and mutation testing of KRAS revealed KRAS amplification in 5 out of 13 (38%) and exon 2 mutations in 6 out of 11 (54%) successfully analyzed cases. A strong correlation was found between KRAS alterations (mutation and/or copy number changes) and intact SMARCB1 expression (7 out of 8; 87%). On the other hand, loss of SMARCB1 expression correlated with the absence of KRAS alterations (3 out of 5 cases; 60%). The results suggest that rhabdoid phenotype in pancreatic undifferentiated rhabdoid carcinomas has a heterogeneous genetic background. SMARCB1 loss is restricted to the anaplastic monomorphic subtype and correlates with the absence of KRAS alterations, whereas the pleomorphic giant cell subtype is characterized by KRAS alterations and intact SMARCB1 expression. Recognition and appropriate subtyping of these rare variants might become necessary for future therapeutic strategies.

Sarcomas With Cic-rearrangements are a Distinct Pathologic Entity With Aggressive Outcome: A Clinicopathologic and Molecular Study of 115 Cases.

CIC-DUX4 gene fusion, resulting from either a t(4;19) or t(10;19) translocation, is the most common genetic abnormality detected in EWSR1-negative small blue round cell tumors. Following their discovery it was debated if these tumors should be classified as variants of Ewing sarcoma (ie, atypical Ewing sarcoma) or as a stand-alone pathologic entity. As such the WHO classification temporarily grouped the CIC-rearranged tumors under undifferentiated sarcomas with round cell phenotype, until further clinical evidence was available. However, most studies reported so far include small series with limited follow-up information, which preclude a more definitive assessment. The present work investigates the clinicopathologic features of a large cohort of sarcomas with CIC gene rearrangement, to define their clinical presentation, morphologic spectrum, and outcome. Our study further examines the overall survival of the CIC-positive cohort compared with a control group of EWSR1-rearranged Ewing sarcoma matched for age and stage. The study cohort included 115 patients, with a mean age of 32 years and a slight male predominance. Most tumors occurred in the soft tissue (86%), predominantly deep-seated and equally divided among trunk and extremity, followed by visceral locations (12%) and rarely in the bone (3%). Microscopically, most tumors showed round to ovoid cytomorphology but half of the cases showed also focal areas of spindling and epithelioid/rhabdoid phenotype, with frequent myxoid stromal changes. Variable CD99 reactivity was seen in 84% cases, with a diffuse pattern only in 23% of cases, whereas nuclear WT1 was seen in 92%. A CIC-DUX4 fusion was detected in 57% of cases, with either DUX4 on 4q35 (35%) or on 10q26 in 25 (22%) cases. No FOXO4 gene rearrangements were present in 39 cases tested. Clinical follow-up was available in 57 patients, with a 5-year survival of 43%, which was significantly lower than the 77% 5-year survival in the control Ewing sarcoma group (P=0.002). Our findings show that CIC-DUX4 sarcomas occur most commonly in young adults within the somatic soft tissues, having a wide spectrum of morphology including round, epithelioid and spindle cells, and associated with an aggressive clinical course, with an inferior overall survival compared with Ewing sarcoma. The results support the classification of CIC-rearranged tumors as an independent molecular and clinical subset of small blue round cell tumors distinct from Ewing sarcoma.

Myxoid variant of so-called angiomatoid "malignant fibrous histiocytoma": clinicopathologic characterization in a series of 21 cases.

Angiomatoid “malignant fibrous histiocytoma” (AMFH) is a tumor of intermediate malignancy and undefined lineage, mostly arising in the extremities of young patients. Examples with a prominent myxoid matrix are very uncommon. Twenty-one cases of myxoid AMFH (among a total of 414) identified in consult files are described, including clinicopathologic features, fluorescence in situ hybridization analysis in a subset of cases, and follow-up. Thirteen patients were female and 8 male, ranging in age from 2 to 51 y (median 17 y). These circumscribed tumors arose in subcutaneous or deep somatic soft tissue, with a median size of 2.5 cm (range, 1 to 8 cm), being located in the extremities (14/21), trunk (4/21), and upper limb girdle (3/21). Characteristic features included a fibrous pseudocapsule (20/21), peritumoral lymphoplasmacytic infiltrates (20/21), blood-filled cystic spaces (17/21), and prominent myxoid morphology comprising 60% to 100% of the tumor surface area examined. Histiocytoid or spindled tumor cells exhibited vesicular nuclei, inconspicuous nucleoli, palely eosinophilic cytoplasm, and multinodular growth without necrosis. Mucin pools and scattered multinucleate giant cells were observed in a subset of cases. Mild to moderate atypia was observed in 4 cases; 1 tumor showed a pseudochondroid matrix. Immunohistochemically, 14/21 cases expressed desmin, 12/21 expressed EMA, and 4/7 exhibited EWSR1 rearrangement. Follow-up, available for 11 patients (median, 43 mo), revealed that 3 developed local recurrence after 2, 7, and 48 months, respectively. All patients were alive without metastases. AMFH may present with prominent myxoid features making diagnosis difficult and causing possible confusion with other myxoid tumors including low-grade fibromyxoid sarcoma, extraskeletal myxoid chondrosarcoma, and myxoid liposarcoma.

Pre-ischaemic exogenous surfactant reduces pulmonary injury in rat ischaemia/reperfusion

The optimal timing of exogenous surfactant application to reduce pulmonary injury and dysfunction was investigated in a rat lung ischaemia and reperfusion injury model. Lungs were subjected to flush perfusion, surfactant instillation, cold ischaemia (4°C, 4 h) and reperfusion (60 min). Animals received surfactant before (group 1) or at the end (2) of ischaemia, or during reperfusion (3) or not at all (4). Control groups included “worst case” without Perfadex and surfactant (5), “no injury” without (6) or with surfactant (7), and ischaemia with pre-ischaemic surfactant (8). Intra-alveolar oedema and blood–air barrier injury were estimated by light and electron microscopic stereology. Perfusate oxygenation and pulmonary arterial pressure (Ppa) were determined during reperfusion in groups 1 to 4. Intra-alveolar oedema was almost absent in groups 1, 6, 7 and 8, pronounced in 2, 3 and 4, and severe in 5. Blood–air barrier injury was moderate in groups 1 and 8, slightly pronounced in 2, 3 and 4, extensive in 5 and almost absent in 6 and 7. Perfusate oxygenation was significantly higher in group 1 compared with groups 2 to 4. Ppa did not differ between the groups. In conclusion, exogenous surfactant attenuates intra-alveolar oedema formation and blood–air barrier damage and improves perfusate oxygenation in the rat lung, especially when applied before ischaemic storage.

Juvenile-like (inflammatory/hyperplastic) mucosal polyps of the gastrointestinal tract in neurofibromatosis type 1.

Diffuse neurofibromatosis/ganglioneuromatosis, solitary/plexiform neurofibroma, periampullary carcinoids and gastrointestinal stromal tumour (GIST) are the main gastrointestinal manifestations of neurofibromatosis type 1 (NF‐1, von Recklinghausen disease). Inflammatory (juvenile‐like) polyps have not been recognised to date as specific gastrointestinal (GI) manifestations of NF‐1.

Exogenous surfactant in ischemia/reperfusion: Effects on endogenous surfactant pools

BACKGROUND Pre-ischemic surfactant treatment attenuates ischemia/reperfusion (I/R) injury. In this study we investigate whether exogenous surfactant acts by influencing endogenous intra-alveolar and intracellular surfactant pools and subtype composition. METHODS Rat lungs from control with (C + S) or without (C - S) surfactant treatment and I/R with (I/R + S) or without (I/R - S) surfactant treatment were analyzed. In I/R groups, lungs underwent ischemic storage for 4 hours at 4 degrees C and reperfusion for 60 minutes. The ultrastructure of intra-alveolar and intracellular surfactant forms fixed in their natural localization and microorganization was investigated by light- and electron-microscopic stereology. RESULTS Only slight differences in alveolar epithelial Type II cell number or volume and lamellar body parameters were observed. Intra-alveolar surfactant volume was significantly enhanced in C + S and I/R + S. I/R increased inactivated surfactant forms (unilamellar vesicles) in untreated [mean (SD): C - S: 26.0% (8.0%) vs I/R - S: 64.8% (5.5%); p < 0.01], but not in surfactant-treated rats [I/R + S: 23.5% (11.5%); p < 0.01 vs I/R - S]. The increase in unilamellar vesicles was closely correlated with intra-alveolar edema and decreased perfusate oxygenation. CONCLUSIONS Attenuation of I/R injury by pre-ischemic exogenous surfactant treatment is mainly based on stabilizing and increasing the active endogenous intra-alveolar surfactant pool.