Rosette-forming glioneuronal tumours are midline, FGFR1-mutated tumours.

AIM: Rosette-forming glioneuronal tumour (RGNT) is a rare central nervous system (CNS) World Health Organization (WHO) grade 1 brain neoplasm. According to the WHO 2021, essential diagnostic criteria are a 'biphasic histomorphology with neurocytic and a glial component, and uniform neurocytes forming rosettes and/or perivascular pseudorosettes associated with synaptophysin expression' and/or DNA methylation profile of RGNT whereas 'FGFR1 mutation with co-occurring PIK3CA and/or NF1 mutation' are desirable criteria. MATERIAL AND METHODS: We report a series of 46 cases fulfilling the essential pathological diagnostic criteria for RGNT. FGFR1 and PIK3CA hotspot mutations were searched for by multiplexed digital PCR in all cases, whereas DNA methylation profiling and/or PIK3R1 and NF1 alterations were analysed in a subset of cases. RESULTS: Three groups were observed. The first one included 21 intracranial midline tumours demonstrating FGFR1 mutation associated with PIK3CA or PIK3R1 (n = 19) or NF1 (n = 1) or PIK3CA and NF1 (n = 1) mutation. By DNA methylation profiling, eight cases were classified as RGNT (they demonstrated FGFR1 and PIK3CA or PIK3R1 mutations). Group 2 comprised 11 cases associated with one single FGFR1 mutation. Group 3 included six cases classified as low-grade glioma (LGG) other than RGNT (one-sixth showed FGFR1 mutation and one a FGFR1 and NF1 mutation) and eight cases without FGFR1 mutation. Groups 2 and 3 were enriched in lateral and spinal cases. CONCLUSIONS: We suggest adding FGFR1 mutation and intracranial midline location as essential diagnostic criteria. When DNA methylation profiling is not available, a RGNT diagnosis remains certain in cases demonstrating characteristic pathological features and FGFR1 mutation associated with either PIK3CA or PIK3R1 mutation.

Be careful with lentils! About a forensic observation.

The discovery of exogenous particles in the broncho-pulmonary tree is frequently described in forensic literature, especially in lung samples, in the context of aspirated gastric content during the death agony period or during resuscitation. We report an original observation of a multi-visceral dispersion of exogenous particles detected, in an 8-year-old boy, who allegedly fell from a 2-m high brick-wall. The autopsy found major liver fracture and diaphragm rupture with massive internal hemorrhage without gastric wall rupture. The histological analyses have identified round to oval bodies in the lung bronchi, alveoli, and, rarely, in vascular sections, and also on the surface of several samples. These particles stained strongly pink by the periodic acid Schiff method, evoking dried vegetables. Two hypotheses were invoked: aspirated vegetable particles into the bronchial tree or parasitic infection, like pinworm larva. In order to characterize the nature of these particles, different legumes were cooked, embedded in paraffin wax, and examined under light microscope. Simultaneously, morphological comparison between the gastric content and pinworm larva and lentils was made and a PCR analysis was performed on gastric fluid sample. The DNA sequencing showed a Fabaceae plant family, Lens culinaris. The possibility of a hematogenous dissemination of the starch grains during a perimortem aspiration of gastric content seems unlikely, and a contamination from the gastric content of the organs samples during the autopsy or the pathologic macroscopic and microscopic processes seems to be the principal hypothesis. The formal identification of such particles is important to avoid the misdiagnosis of a potential parasitic infection. The risk of confusion can be detrimental in some circumstances.

Prognostic Relevance of Histomolecular Classification of Diffuse Adult High-Grade Gliomas with Necrosis.

Diffuse adult high-grade gliomas (HGGs) with necrosis encompass anaplastic oligodendrogliomas (AOs) with necrosis (grade III), glioblastomas (GBM, grade IV) and glioblastomas with an oligodendroglial component (GBMO, grade IV). Here, we aimed to search for prognostic relevance of histological classification and molecular alterations of these tumors. About 210 patients were included (63 AO, 56 GBM and 91 GBMO). GBMO group was split into "anaplastic oligoastrocytoma (AOA) with necrosis grade IV/GBMO," restricted to tumors showing intermingled astrocytic and oligodendroglial component, and "GBM/GBMO" based on tumors presenting oligodendroglial foci and features of GBM. Genomic arrays, IDH1 R132H expression analyses and IDH direct sequencing were performed. 1p/19q co-deletion characterized AO, whereas no IDH1 R132H expression and intact 1p/19q characterized both GBM and GBM/GBMO. AOA with necrosis/GBMO mainly demonstrated IDH1 R132H expression and intact 1p/19q. Other IDH1 or IDH2 mutations were extremely rare. Both histological and molecular classifications were predictive of progression free survival (PFS) and overall survival (OS) (P < 10(-4) ). Diffuse adult HGGs with necrosis can be split into three histomolecular groups of prognostic relevance: 1p/19q co-deleted AO, IDH1 R132H-GBM and 1p/19q intact IDH1 R132H+ gliomas that might be classified as IDH1 R132H+ GBM. Because of histomolecular heterogeneity, we suggest to remove the name GBMO.

[An unusual cause of pancytopenia: intravascular lymphoma]. / Etiologie inhabituelle d'une pancytopénie: le lymphome intravasculaire.

We report an observation of intravascular lymphoma occurring in a 69-year-old woman. This relatively rare disease presents polymorphic clinical features that render diagnosis difficult. Cutaneous and central nervous system signs and symptoms are frequently observed and should be recognized as suggestive of intravascular lymphoma. However, they are not always observed, in our case only pancytopenia was present. Pronostic is generally unfavorable but good response to chemotherapy has been described with early diagnosis. A large number of pathogenic hypotheses have been put forward: abnormality of cellular receptor, role of Epstein-Barr virus or transformation from lymphoma. Intravascular lymphoma should be included in the differential diagnosis of pancytopenia to increase chances of good response.

Borrelia burgdorferi-associated lymphocytoma cutis simulating a primary cutaneous large B-cell lymphoma.

The distinction between primary cutaneous B-cell lymphoma and B-cell pseudolymphoma on a histologic basis may be difficult, particularly in some cases of Borrelia burgdorferi-associated lymphoid proliferations. We report two cases of B. burgdorferi-associated pseudolymphoma that showed a dense infiltrate with a predominance of large atypical B cells. Because of this misleading histologic feature, a diagnosis of primary cutaneous large B-cell lymphoma was first suspected in both cases. In one case, successive recurrences led to aggressive therapies before the B. burgdorferi infection was recognized. However, a detailed review of histologic and immunohistochemical features was finally suggestive of a B. burgdorferi-associated pseudolymphoma in both cases. The etiologic role of B. burgdorferi was confirmed by serology, polymerase chain reaction analysis of B. burgdorferi DNA within the lesional skin, and response to antibiotic therapy. Because the distinction between B. burgdorferi-associated pseudolymphoma and primary cutaneous B-cell lymphomas may be difficult and true B. burgdorferi-associated B-cell lymphomas have been described, we suggest that antibiotic therapy should be considered as a first-line treatment in suspected or confirmed cases of primary cutaneous B-cell lymphoma in regions with endemic B. burgdorferi infection.