A rare case of Pneumocystis jirovecii and cytomegalovirus coinfection in the small bowel

Introduction/Objective

Infection with Pneumocystis jirovecii remains a common cause of pneumonia in patients with Acquired Immune Deficiency Syndrome (AIDS). Extrapulmonary manifestations, however, are exceedingly rare. We describe a rare case of coinfection of the small bowel by Pneumocystis jirovecii and cytomegalovirus (CMV).

Methods/Case Report

A 48-year-old female with a history of HIV/AIDS, remote history of Pneumocystis jirovecii pneumonia, and previous non-compliance with HAART, presented to the emergency department with right lower quadrant abdominal pain, fever, and chills for 1 week. Her recent medical history included a hospital admission 1 month prior for community-acquired pneumonia with CD4 count and viral load of 12 cells/mcl and >680,000 copies/mL, respectively; upon discharge she restarted HAART. When she presented to the emergency department in our case, she demonstrated leukocytosis (14.3 K/mcl), tachycardia (131 bpm), and hypotension (87/58 mmHg). An abdominal CT scan showed free air with concern for perforated viscus and multi-station lymphadenopathy with gastrohepatic and retrocaval nodes >2 cm. A chest x-ray showed nodular and cavitary lesions, stable from prior imaging. The differential diagnoses in an AIDS patient with a gastrointestinal mass includes Kaposi’s sarcoma, lymphoproliferative process, or infection. The surgeons were concerned for tuberculosis as well, due to the hospital’s patient population, her bulky lymphadenopathy, and immune-compromised status. An exploratory laparotomy was performed and found jejunal perforations, mesenteric lymphadenopathy, and 3L of fluid in the abdomen. Pathology received 4 soft lymph nodes and a 57 cm segment of thickened small bowel with purulent perforation but no discrete mass. Microscopic examination showed a perforating pseudotumor and acute serositis extending to the margins of the specimen. Lymph node flow cytometry was negative for clonal populations. GMS stains highlighted innumerable “crushed-ping-pong-ball”-like fungal forms consistent with Pneumocystis in the jejunum and all 4 lymph nodes. A CMV immunohistochemical stain highlighted infected cells with nuclear enlargement and nuclear inclusions in the jejunum.

Results (if a Case Study enter NA)

NA

Conclusion

Extrapulmonary Pneumocystis infection is rare but clinicians, pathologists, and microbiologists must keep it in the differential of HIV patients, especially those who are not controlled on antiretroviral therapy.

Metastatic small bowel adenocarcinoma: role of metastasectomy and systemic chemotherapy

Background

Metastatic small bowel adenocarcinoma (SBA) has a poor prognosis. Due to its rarity, high-quality data are lacking to guide treatment. This retrospective analysis was conducted to help characterize the treatment options for patients with metastatic SBA while providing clinically meaningful prognostic information.

Patients and methods

In total, 437 patients who initially presented with or developed metastatic SBA between September 1977 and September 2019 were identified from the MD Anderson Tumor Registry. Clinical data were collected from review of the medical record. Overall response rates (ORR), time to progression (TTP), and overall survival (OS) were assessed across various treatments and treatment lines.

Results

The median OS from diagnosis of metastatic disease was 15.9 months [95% confidence interval (CI): 14.3-17.9]. Seventy-five patients (17.1%) underwent metastasectomy, which was associated with a median OS of 34.5 versus 17.1 months among patients who received chemotherapy alone (P < 0.001). Fluoropyrimidine plus platinum (n = 164) was the most common first-line chemotherapy, associated with an ORR of 59% and TTP of 8.1 months. Irinotecan with 5-FU (n = 101) was the most common second-line therapy associated with an ORR of 31% and TTP of 4.0 months. Twenty-two patients received immunotherapy; 5 of 6 patients with deficient mismatch repair (dMMR) responded, while 0 of 16 with proficient mismatch repair (pMMR) responded. Taxane-based chemotherapy was given to 34 patients with an ORR of 21% and a median TTP of 2.4 months. Among 11 patients who received anti-epidermal-growth-factor-receptor (EGFR) monotherapy, the best response was stable disease (SD) in 1 patient.

Conclusions

In well-selected patients with SBA, metastasectomy appears to be associated with improved OS. This improvement was seen across metastasectomy sites, including liver, lung and peritoneal. Anti-programmed cell death protein 1 (PD-1) based immunotherapy was active for dMMR SBA but not pMMR SBA. While taxane-based chemotherapy demonstrates therapeutic activity, the activity of anti-EGFR therapy was limited.

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Metastasectomy for well-selected metastatic SBA patients was associated with improved OS.

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Anti-PD1-based immunotherapy was active for dMMR SBA but not pMMR SBA.

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Taxane-based chemotherapy demonstrated clinical activity in refractory SBA.

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Anti-EGFR therapy demonstrated minimal activity in SBA.

Human type II arginase: sequence analysis and tissue-specific expression

A full-length cDNA encoding type II arginase was isolated from a human kidney cDNA library and its sequence compared to those of vertebrate type I arginases as well as to arginases of bacteria, fungi and plants. The predicted sequence of human type II arginase is 58% identical to the sequence of human type I arginase but is 71% identical to the sequence of Xenopus type II arginase, suggesting that duplication of the arginase gene occurred before mammals and amphibians diverged. Seven residues known to be essential for activity were found to be conserved in all arginases. Type II arginase mRNA was detected in virtually all human and mouse RNA samples tested whereas type I arginase mRNA was found only in liver. At least five mRNA species hybridizing to type II arginase cDNA were found in the human RNA samples whereas only a single type II arginase mRNA species was found in the mouse. This raises the possibility that the multiple type II arginase mRNAs in humans arise from differential RNA processing or usage of alternative promoters.