Gastrointestinal lymphomas: Morphology, immunophenotype and molecular features

Phyllodes tumors (PTs) of the breast are biphasic lesions, comprising an epithelial component set within a neoplastic spindle-celled stroma. These tumors have been classified as benign, borderline, and malignant based on a combination of histological criteria, including stromal cellularity, nuclear pleomorphism, mitotic rate, stromal overgrowth, and margin appearance. The aim of this study was to evaluate the expression of CD34, CD117 (c-kit), and Ki-67 in PT of the breast and attempt to correlate the staining pattern with tumor grade by morphology. Immunohistochemical expression of CD117, CD34, and Ki-67 was studied on formalin-fixed, paraffin-embedded archival tissue material from 33 cases of PT. Histologically, there were 21 benign, 6 borderline, and 6 malignant (high-grade) tumors. All 6 histologically malignant PTs were positive for CD117 (100%), but only 1 marked with CD34 (16.7%). Borderline PTs frequently coexpressed CD34 and CD117 (66.7%). The benign PTs, on the other hand, most commonly (52.4%) showed a CD34(+)/CD117(-) immunoprofile with 33.3% cases coexpressing the markers: that is, CD34(+)/CD117(+). Although most benign PTs (80.6%) showed a Ki-67 of <2%, a few cases showed slightly higher proliferation indices. This study indicates that CD34 and CD117 are differentially expressed in benign and malignant PTs. These markers, therefore, in combination, may be used as an adjunct to morphology in the subclassification of PTs.

The functional and prognostic implications of regulatory T cells in colorectal carcinoma

We report a 49-year-old Chinese male with locally advanced gastric adenocarcinoma achieving pathological complete response after neoadjuvant chemotherapy with trastuzumab-containing regimen. He underwent esophagogastroduodenoscopy in September 2009, which revealed a 2-cm gastric ulcer on the lesser curvature proximal to angularis. Biopsy of gastric ulcer showed moderately differentiated adenocarcinoma with overexpression of human epidermal growth factor receptor 2 (HER2) by immunohistochemistry and fluorescence in situ hybridization. Further workups with endoscopic ultrasound, computed tomography and positron emission tomography staged his cancer as T3N1M0. He received 3 cycles of neoadjuvant chemotherapy consisting of trastuzumab, oxaliplatin, docetaxel and capecitabine without severe toxicities except grade 2 diarrhea near the completion of cycle 3 requiring discontinuation of capecitabine. Afterwards, he received total gastrectomy with extended D2 lymph node dissections showing pathological complete response. He went on to receive 3 more cycles of chemotherapy postoperatively. The role of trastuzumab as a part of perioperative therapy in gastric cancer overexpressing HER2 is worth further investigation.

Post-transplant lymphoproliferative disorders (PTLDs) are lymphoid or plasmacytic proliferations ranging from polyclonal reactive proliferations to overt lymphomas that develop as consequence of immunosuppression in recipients of solid organ transplantation (SOT) or allogeneic bone marrow/hematopoietic stem cell transplantation. Immunosuppression and Epstein–Barr virus (EBV) infection are known risk factors for PTLD. Patients with documented histopathologic diagnosis of primary PTLD at our institution between January 2000 and October 2019 were studied. Sixty-six patients with PTLD following SOT were followed for a median of 9.0 years. The overall median time from transplant to PTLD diagnosis was 5.5 years, with infant transplants showing the longest time to diagnosis at 12.0 years, compared to pediatric and adolescent transplants at 4.0 years and adult transplants at 4.5 years. The median overall survival (OS) was 19.0 years. In the monomorphic diffuse large B-cell (M-DLBCL-PTLD) subtype, median OS was 10.7 years, while median OS for polymorphic subtype was not yet reached. There was no significant difference in OS in patients with M-DLBCL-PTLD stratified by quantitative EBV viral load over and under 100,000 copies/mL at time of diagnosis, although there was a trend towards worse prognosis in those with higher copies.