Rectal Tonsil in a Patient With Positive Syphilis Serology.

Rectal tonsils are an abnormal reactive proliferation of lymphoid tissue in the rectum. Typical lymphoid tissue of the colon and rectum can proliferate with an increased number of germinal centers in response to exposure to an antigen in the GI tract. This response, in rare cases, escalates to the proliferation of a lymphoid mass known as a rectal tonsil. Here, we present a case of a 46-year-old woman with iron deficiency anemia who underwent colonoscopy with incidental finding of a rectal tonsil. This report discusses initial clinical workup, colonoscopy findings, pathological analysis, subsequent testing, and surgical removal of the identified mass and this rare finding.

MEF2B is a member of the BCL6 gene transcriptional complex and induces its expression in diffuse large B-cell lymphoma of the germinal center B-cell-like type.

Myocyte enhancer-binding factor 2B (MEF2B) has been implicated as a transcriptional regulator for BCL6. However, details about the interaction between MEF2B and BCL6 during expression, as well as the relationship of MEF2B to the expression of other germinal center (GC) markers, have not yet been fully explained. Using germinal center B-cell-like diffuse large B-cell lymphoma (GC-DLBCL) and activated B-cell diffuse large B-cell lymphoma (ABC-DLBCL) cell lines, we analyzed the expression of MEF2B and its associations with BCL6, CD10, and ERK. Furthermore, small interfering RNA (siRNA) was used to study the possible effects of MEF2B knockdown on these proteins and cell growth. Analysis of the BCL6 transcriptional complex was performed using electrophoretic mobility shift assay. The correlation between MEF2B expression and the genetic type of DLBCL was assessed using immunohistochemistry on 111 patient samples, and via in silico analysis of publicly available microarray (Gene Expression Omnibus (GEO)) datasets. Our results indicate that the expression of MEF2B protein is important for the growth of GC-DLBCL cells, as evidenced by MEF2B knockdown inhibition of cell growth and the subsequent suppression of BCL6, CD10, and ERK phosphorylation. Analysis of BCL6 transcription factors in nuclear extracts of MEF2-expressing DLBCL cells showed involvement of MEF2B with AP-2α and BCL6 proteins in the formation of the BCL6 gene transcriptional complex. Indeed, differential expression of MEF2B in the GC-DLBCL is statistically significant compared to the ABC-DLBCL in the GEO datasets, as well as in tissue microarray, as indicated via immunohistochemistry (Visco-Young algorithm). Our findings indicate that MEF2B is an essential component of the BCL6 gene transcriptional complex for the regulation of DLBCL growth via the promotion of BCL6 expression. Beyond its regulatory role in DLBCL growth, MEF2B expression correlated positively with BCL6 and CD10 expression, and was preferentially expressed in the GBC-DLBCL group.

Sellar and Suprasellar Anaplastic Hemangiopericytoma in a 34-Year Old Man.

Central nervous system hemangiopericytomas are rare, representing <1% of all primary central nervous system tumors. Hemangiopericytomas of the sellar region are exceptionally rare. Here we present a case of a sellar/suprasellar anaplastic hemangiopericytoma.The patient is a 34 year old man with a history of a resected pituitary tumor, diagnosed as a pituitary adenoma per the patient, who presented with bitemporal hemianopsia. Radiology revealed a 3.7 cm enhancing sellar/suprasellar mass with local mass effect, consistent with a pituitary adenoma. On resection, the mass was diagnosed as anaplastic hemangiopericytoma, WHO grade III. The patient experienced residual tumor with two further resections before expiring of a pulmonary embolus seven months later.There are only 10 previously documented cases of sellar/suprasellar hemangiopericytoma in the English-speaking world literature. This is the third case of anaplastic hemangiopericytoma in this region. These cases should be recorded until meaningful conclusions about therapy and prognosis can be established.

Methotrexate-associated primary cutaneous CD30-positive cutaneous T-cell lymphoproliferative disorder: a case illustration and a brief review.

Methotrexate (MTX) is a commonly used anti-metabolite agent. Increased risk of lymphoproliferative disorders (LPD) in patients with rheumatoid arthritis (RA) has been documented with the prolonged use of immunosuppressive medications such as MTX. This is thought to be the result of immune dysregulation and/or chronic immune stimulation. Most cases of LPDs regress following withdrawal of the offending immunosuppressive agent. We present an interesting and rare case of CD30 and EBV positive CD8 primary cutaneous anaplastic large cell lymphoma (PC-ALCL) in a 66-year-old African American woman. Patient had been on MTX for rheumatoid arthritis (RA) which was stopped after the patient was evaluated at our institution. Patient had an incredible response to stopping immunosuppression with spontaneous regression of skin lesions and disappearance of clonal malignant cell population as evidenced on serial biopsy specimens. Primary cutaneous CD30+ LPDs constitute about 30% of the primary cutaneous T-cell lymphomas (CTLs) and includes entities such as lymphomatoid papulosis (LyP), primary cutaneous anaplastic large cell lymphoma (PC-ALCL) and other CD30+ borderline LPDs. Histopathological criteria in addition to CD30 positivity is important for identification of these conditions. Treatment options include "wait and see", phototherapy, radiotherapy, topical agents, systemic therapy and surgical resection. Prognosis is excellent and most cases resolve spontaneously on withdrawal of immunosuppression. Refractory cases may require aggressive local treatment or systemic therapy. Brentuximab Vedontin, an anti-CD30 antibody drug conjugate (ADC), may provide additional therapeutic option in refractory cases.

Syncytial Variant of Nodular Sclerosis Classical Hodgkin Lymphoma of the Terminal Ileum in a Patient with Longstanding Crohn's Disease.

Primary Hodgkin lymphoma of the gastrointestinal tract is an uncommon malignancy with few reported cases. Here we describe a rare variant of Hodgkin lymphoma presented in the gastrointestinal tract in association with Crohn's Disease.The patient is a 58 year old male with a 40 year history of formerly well-controlled Crohn's disease who presented with abdominal discomfort and constitutional symptoms. Computed tomography showed a 10 cm thickened segment of ileum and a dilated segment of small bowel. The patient underwent segmental resection, revealing a mass, which was diagnosed by pathology as nodular sclerosis classical Hodgkin lymphoma, syncytial variant.There are only 29 reported cases of syncytial variant of nodular sclerosis classical Hodgkin lymphoma. This is the second documented case of primary gastrointestinal syncytial variant of nodular sclerosis classical Hodgkin lymphoma. Further characterization of this entity is necessary.