Case Report: Malakoplakia Developing in the Graft Colon Post Intestinal Transplant

Casestudy

Malakoplakia is a rare chronic granulomatous disease thought to be caused by a macrophage bactericidal defect and most commonly affecting the genitourinary tract. Most cases are associated with chronic infections or immunosuppression, with most transplant related cases observed after renal transplantation.

Results

A male in his thirties developed short gut syndrome secondary to injuries and subsequently underwent a small and large bowel transplant and was treated with immunosuppressive medications.

He developed multiple episodes of acute rejection and multiple infectious foci, including a peri-rectal fluid accumulation growing Escherichia Coli, bacteremia with Klebisella oxytica, and Epstein Barr Virus viremia. Functional imaging revealed increased activity in mesenteric lymph nodes and in the peri-rectal fluid accumulation. On endoscopy, a rectal ulcer associated with mucosal protuberance was noted and tissue was obtained for pathologic diagnosis.

Histologic examination revealed mucosal infiltration by numerous macrophages with abundant granular cytoplasm. Michaelis-Gutmann bodies (considered pathognomonic for malakoplakia) were identified showing PAS and Von- Kossa positivity. Acid fast stain was negative. These findings supported the diagnosis of malakoplakia.

Other differential diagnoses were considered, including post-transplant lymphoproliferative disorder, neoplasia, infection with mycobacterial or fungal species, and secondary hemophagocytic lymphohistiocytosis syndrome. These were excluded based on the characteristic histologic findings.

Given the diagnosis, treatment with oral antibiotics was attempted. Follow up biopsies revealed disease persistence and the patient was transitioned to a prolonged course of intravenous antibiotics and bethanechol, with eventual histologic response. Unfortunately, due to stenosis and adhesions that developed secondary to the episodes of acute rejection, the patient eventually underwent graft explanation.

Conclusion

Our case highlights the risk factor milieu encountered in intestinal transplant patients and the prolonged treatment often required to treat malakoplakia. Additionally, malakoplakia constitutes an unusual consideration in intestinal transplant patients and prompt diagnosis is required to direct proper management of these patients.

Prognostic Marker Expression In Microinvasive Breast Cancer

Introduction/Objective

Microinvasive breast carcinoma (Mi) is defined as invasive carcinoma (IC) less than 1 mm in greatest dimension. Depletion of the focus during further immunohistochemical investigation is commonly observed. Studies on prognostic marker expression report high concordance between the Mi and concomitant ductal carcinoma in-situ (DCIS). Compared to IC, Mi has a higher rate of Her2 positivity, indicating aggressive phenotype and potential variation in marker expression over time. We aimed to verify the concordance between Mi and DCIS in patients with pure Mi, as well as between foci of Mi and IC in patients with both.

Methods

A total of 21 cases of Mi and 9 cases with both IC and Mi disease were identified and evaluated for pathologic characteristics and ER, PR, and Her2 expression by immunohistochemistry. The rate of Her2 in Mi was compared to national benchmarks for IC.

Results

Mi was associated with high grade DCIS. 100% concordance of Her2 expression between Mi and DCIS was present in 14/21 cases where Mi was not depleted. Discrepancy between ER/PR was seen in two cases (Mi negative/DCIS focally positive). 50% of these Mi cases were Her2 positive, compared to the 13–25% generally reported for IC. Overall, by extrapolating Mi status from the concomitant DCIS when the Mi became depleted, 38% of Mi was positive for Her2. 100% concordance between foci of Mi and IC in patients presenting with both was observed.

Conclusion

Mi had a more aggressive prognostic marker phenotype compared to IC based on Her2 positivity. Concordance of prognostic marker expression between Mi and concomitant DCIS supports reporting of the DCIS status when the Mi becomes depleted, with only rare ER/PR discrepancies observed. Concordance between foci of Mi and IC in patients with both does not support time-based variation in marker expression. However, further investigation is warranted to uncover potential changes.

Overexpression of T-bet in HIV infection is associated with accumulation of B cells outside germinal centers and poor affinity maturation

Nearly all chronic human infections are associated with alterations in the memory B cell (MBC) compartment, including a large expansion of CD19hiT-bethi MBC in the peripheral blood of HIV-infected individuals with chronic viremia. Despite their prevalence, it is unclear how these B cells arise and whether they contribute to the inefficiency of antibody-mediated immunity in chronic infectious diseases. We addressed these questions by characterizing T-bet-expressing B cells in lymph nodes (LN) and identifying a strong T-bet signature among HIV-specific MBC associated with poor immunologic outcome. Confocal microscopy and quantitative imaging revealed that T-bethi B cells in LN of HIV-infected chronically viremic individuals distinctly accumulated outside germinal centers (GC), which are critical for optimal antibody responses. In single-cell analyses, LN T-bethi B cells of HIV-infected individuals were almost exclusively found among CD19hi MBC and expressed reduced GC-homing receptors. Furthermore, HIV-specific B cells of infected individuals were enriched among LN CD19hiT-bethi MBC and displayed a distinct transcriptome, with features similar to CD19hiT-bethi MBC in blood and LN GC B cells (GCBC). LN CD19hiT-bethi MBC were also related to GCBC by B cell receptor (BCR)-based phylogenetic linkage but had lower BCR mutation frequencies and reduced HIV-neutralizing capacity, consistent with diminished participation in GC-mediated affinity selection. Thus, in the setting of chronic immune activation associated with HIV viremia, failure of HIV-specific B cells to enter or remain in GC may help explain the rarity of high-affinity protective antibodies.

Lymph Node Cellular Dynamics in Cancer and HIV: What Can We Learn for the Follicular CD4 (Tfh) Cells?

Lymph nodes (LNs) are central in the generation of adaptive immune responses. Follicular helper CD4 T (Tfh) cells, a highly differentiated CD4 population, provide critical help for the development of antigen-specific B cell responses within the germinal center. Throughout the past decade, numerous studies have revealed the important role of Tfh cells in Human Immunodeficiency Virus (HIV) pathogenesis as well as in the development of neutralizing antibodies post-infection and post-vaccination. It has also been established that tumors influence various immune cell subsets not only in their proximity, but also in draining lymph nodes. The role of local or tumor associated lymph node Tfh cells in disease progression is emerging. Comparative studies of Tfh cells in chronic infections and cancer could therefore provide novel information with regards to their differentiation plasticity and to the mechanisms regulating their development.

The Lymph Node in HIV Pathogenesis

Lymph nodes play a central role in the development of adaptive immunity against pathogens and particularly the generation of antigen-specific B cell responses in specialized areas called germinal centers (GCs). Lymph node (LN) pathology was recognized as an important consequence of human immunodeficiency virus (HIV) infection since the beginning of the HIV epidemic. Investigation into the structural and functional alterations induced by HIV and Simian immunodeficiency virus (SIV) has further cemented the central role that lymphoid tissue plays in HIV/SIV pathogenesis. The coexistence of constant local inflammation, altered tissue architecture, and relative exclusion of virus-specific CD8 T cells from the GCs creates a unique environment for the virus evolution and establishment of viral reservoir in specific GC cells, namely T follicular helper CD4 T cells (Tfh). A better understanding of the biology of immune cells in HIV-infected lymph nodes is a prerequisite to attaining the ultimate goal of complete viral eradication.

Quantitative Multiplexed Imaging Analysis Reveals a Strong Association between Immunogen-Specific B Cell Responses and Tonsillar Germinal Center Immune Dynamics in Children after Influenza Vaccination

Generation of Ag-specific humoral responses requires the orchestrated development and function of highly specialized immune cells in secondary lymphoid organs. We used a multiparametric approach combining flow cytometry, confocal microscopy, and histocytometry to analyze, for the first time to our knowledge in children, tonsils from seasonal influenza-vaccinated children. We used these novel imaging assays to address the mucosal immune dynamics in tonsils investigating the spatial positioning, frequency, and phenotype of immune cells after vaccination. Vaccination was associated with a significantly higher frequency of follicular helper CD4 T cells compared with the unvaccinated control group. The imaging analysis revealed that potential suppressor (FOXP3^hi) CD4 T cells are mainly located in extrafollicular areas. Furthermore, a significantly reduced frequency of both follicular and extrafollicular FOXP3^hi CD4 T cells was found in the vaccine group compared with the control group. Levels of circulating CXCL13 were higher in those vaccinated compared with controls, mirroring an increased germinal center reactivity in the tonsils. Notably, a strong correlation was found between the frequency of tonsillar T follicular helper cells and tonsillar Ag-specific Ab-secreting cells. These data demonstrate that influenza vaccination promotes the prevalence of relevant immune cells in tonsillar follicles and support the use of tonsils as lymphoid sites for the study of germinal center reactions after vaccination in children.