SETD2 and histone H3 lysine 36 methylation deficiency in advanced systemic mastocytosis.

The molecular basis of advanced systemic mastocytosis (SM) is not fully understood and despite novel therapies the prognosis remains dismal. Exome sequencing of an index-patient with mast cell leukemia (MCL) uncovered biallelic loss-of-function mutations in the SETD2 histone methyltransferase gene. Copy-neutral loss-of-heterozygosity at 3p21.3 (where SETD2 maps) was subsequently found in SM patients and prompted us to undertake an in-depth analysis of SETD2 copy number, mutation status, transcript expression and methylation levels, as well as functional studies in the HMC-1 cell line and in a validation cohort of 57 additional cases with SM, including MCL, aggressive SM and indolent SM. Reduced or no SETD2 protein expression-and consequently, H3K36 trimethylation-was found in all cases and inversely correlated with disease aggressiveness. Proteasome inhibition rescued SETD2 expression and H3K36 trimethylation and resulted in marked accumulation of ubiquitinated SETD2 in SETD2-deficient patients but not in patients with near-normal SETD2 expression. Bortezomib and, to a lesser extent, AZD1775 alone or in combination with midostaurin induced apoptosis and reduced clonogenic growth of HMC-1 cells and of neoplastic mast cells from advanced SM patients. Our findings may have implications for prognostication of SM patients and for the development of improved treatment approaches in advanced SM.

[The sentinel lymph node in melanoma: utilization of molecular biology (RT-PCR) to detect occult metastases]. / II linfonodo sentinella nel melanoma: utilizzo della biologia molecolare (RT-PCR) nella ricerca delle metastasi occulte.

Sentinel lymph node (SLN) analysis allows the detection of occult metastases in patients with melanoma. The use of serial sections and immunohistochemical investigations (ICH) increases the chance of identifying metastases. Nevertheless, detection of mRNA of the tyrosinase gene through reverse transcription-polymerase chain reaction (RT-PCR) is the most sensitive tool for detection of occult melanoma cells in SLN. From September 1999 to August 2001, in the Anatomic Pathology Unit of M. Bufalini Hospital of Cesena, 489 SLNs from 332 patients with primary melanoma in clinical stages I and II (according to AJCC) were examined. There were 66 (13.5%) SLNs and 58 (17.4%) cases with metastasis revealed by histology and ICH. A single case with metastatic SLN was found in patients with melanomas < or = 1 mm in thickness. The percentage of cases with metastases in SLN correlated with thickness of the primary melanoma (p < 0.0001). RT-PCR for tyrosinase was carried out in 448 SLNs from of 308 cases. Overall, the RT-PCR results were positive in 149 (48.4%) patients and in 169 SLNs (37.9%). RT-PCR results showed a strong positive correlation with tumor thickness of primary melanoma (p < 0.0001) and with the clinical stage (p < 0.0001). Of the RT-PCR-positive cases, 18 showed intracapsular aggregates of nevus cells. Besides the percentage of positive cases, once those with nevus aggregates were excluded, overall, the RT-PCR revealed the presence of tyrosinase mRNA in 34.5% of patients with negative histology and ICH. Ongoing monitoring is necessary to define the real prognostic implication of the presumed presence of occult melanoma deposits disclosed by RT-PCR in SLNs.

[Cell-block immunocytochemical characterization of effusions. Use of antibody panel: calretinin, Ber-EP4, keratin and CD68]. / Caratterizzazione immunocitochimica dei versamenti su citoincluso. Applicazione del pannello anticorpale: calretinina, Ber-EP4, cheratina e CD68.

An anticorpal panel formed by Calretinin, Ber-EP4, Keratin and CD 68 has been applied to differentiate mesothelial hyperplasia/mesothelioma from metastastic carcinoma in cavity effusions. The study was performed in 86 cases in which paraffinated cell-blocks were obtained. All cases positive for malignancy had histological confirmation. The series included 2 malignant mesothelioma, 54 reactive mesothelial hyperplasia, and 30 metastatic carcinoma. All cases of reactive mesothelial showed strong cytoplasmatic positivity for Calretinin, and hyperplasia negativity for Ber-EP4. The 2 cases of mesothelioma were positive for Calretinin and negative for Ber-EP4. In contrast, all cases of metastatic carcinoma had membrane or cytoplasmatic positivity for Ber-EP4. The sensitivity (100%) and specificity (100%) of reactivity for Calretinin and Ber-EP4 showed that the immunocytochemical results on paraffin embedded material from cavity effusions are very reliable, so that the tested immunocytochemical panel can be useful in cytological differential diagnosis between reactive mesothelial hyperplasia/mesothelioma and metastatic carcinoma.

[Anatomo-pathologic study of sentinel lymph nodes in melanoma. Analysis of 200 cases]. / Studio anatomo-patologico del linfonodo sentinella nei melanomi. Analisi di 200 casi.

Pathologic evaluation of sentinel lymph node represents a new technique for managing high-risk primary melanoma. We examined the sentinel lymph node biopsies of 200 patients affected by primary melanomas of trunk, limbs, head and neck, who had been operated at "M. Bufalini" Hospital between April 1996 and July 1998. The lymphatic mapping has been performed through the preoperative intradermal injection of vital blue dye and technetium-labelled albumin. 319 sentinel lymph nodes were harvested and the 11.3% (15% of patients) were positive for melanoma metastases. No metastases were found in melanomas < or = 1 mm. The percentage of positive sentinel lymph nodes in patients with melanomas > 1 mm in thickness was 16.3% (22% of patients). In 5 cases (2.5%) nodal nevi were found, 1 of which was associated with micrometastasis. All 30 patients with positive sentinel lymph nodes underwent regional lymph node dissection and 555 lymph nodes were harvested. Melanoma metastases were found in only 7 patients, in 31 lymph nodes. The procedure of SLN detection and biopsy is a feasible surgical approach to melanoma patients. It is extremely useful in finding early metastases and in effective pathologic staging. As a consequence of the very low incidence of metastases in the sentinel lymph nodes of patients with thin melanomas, we suggest the sentinel lymph node mapping should be offered to patients with primary melanomas at least 1 mm in depth.

Intracranial desmoplastic small-cell tumor. Report of a case.

We report a case of desmoplastic small-cell tumor occurring in the CNS in relation to the tentorium in a 24-year-old man. Morphologically, the neoplasm had the typical appearance of small, round tumor cells of primitive appearance growing as well-defined nests separated by abundant desmoplastic stroma. The diagnosis was confirmed through the demonstration of immunoreactivity for keratin, desmin, and neuron-specific enolase and the detection by Southern blot analysis of a unique gene resulting from the fusion of the WT1 gene in chromosome 11 and the EWS gene in chromosome 22. This is the first documented instance of the occurrence of this tumor type at a distance from a mesothelial-lined surface.