Mycobacterium genavense-induced spindle cell pseudotumor in a pediatric hematopoietic stem cell transplant recipient: Case report and review of the literature

Prevalence and Characteristics of Non-tuberculous Mycobacteria (NTM) Infection in Recipients of Allogeneic Hematopoietic Stem Cell Transplantation: a Systematic Review and Meta-analysis

PURPOSE

Non-tuberculous mycobacteria (NTM) infections in hematopoietic stem cell transplantation (HSCT) recipients represent a diagnostic and therapeutic challenge. Here, we aimed to review and analyze current literature on incidence, clinical presentation, and outcome of NTM infection after allogeneic HSCT.

METHODS

We performed a systematic review and meta-analysis of available literature regarding NTM infection in children and adults receiving allogeneic HSCT.

RESULTS

We identified 56 articles eligible for the analysis. Among 15 studies, describing 15,798 allogeneic HSCT, we estimated a prevalence of 1.26% (95% CI 0.72, 1.93) of NTM after transplant. Analysis of 175 patients with NTM infection showed a median time of diagnosis of 318 days after HSCT, an increased prevalence in adults (82.9%), and a most frequent pulmonary involvement (44%). Comparison between children and adults revealed an earlier post-transplant disease onset (median 130 days vs 287 days) and most frequent non-pulmonary presentation in children. A vast heterogeneity of therapeutic approach reflected the lack of universal recommendations regarding drug combination and duration of therapy. Overall, NTM-related mortality accounted for 33% in this systematic review.

CONCLUSION

Although rare, NTM infections can complicate post-transplant course with a high mortality rate in children and adults. The lack of prospective studies and guidelines prevents identification of risk factors and therapeutic recommendations.

Pseudotumor of the skin due to Mycobacterium genavense

Mycobacterium genavense is a rare type of nontuberculous Mycobacterium that has been reported to cause disseminated infections in patients who are immunocompromised. Because M. genavense is slow-growing and poorly able to form colonies on Ogawa medium, genetic and molecular analyses are necessary to identify this pathogen. Nontuberculous Mycobacterium infections present with various cutaneous manifestations. Of these, rare cases have been reported to present with mycobacterial pseudotumors. However, there are no reports of M. genavense with cutaneous pseudotumors. In this paper, we report a case of a pseudotumor due to M. genavense infection that was observed only in a cutaneous lesion. The patient was taking 5 mg of prednisolone and was aware of a tumor on the right lower leg. Biopsy samples showed diffuse spindle-shaped histiocytes and various other inflammatory cell infiltrates, and Ziehl-Neelsen staining detected Mycobacterium. Because no colonies formed on the Ogawa medium, genetic testing was performed, and M. genavense was identified by DNA sequence analysis. There were no other disseminated lesions beyond the skin, including in the lungs and liver. Because the patient was immunosuppressed, in accordance with previous literature, a combination therapy of clarithromycin, ethambutol, and rifampicin for 4 months was recommended. When no growth is observed on the Ogawa medium in cases of infection, it is essential to identify the infectious pathogen by genetic analysis.

Advances in Pluripotent Stem Cells: History, Mechanisms, Technologies, and Applications

Over the past 20 years, and particularly in the last decade, significant developmental milestones have driven basic, translational, and clinical advances in the field of stem cell and regenerative medicine. In this article, we provide a systemic overview of the major recent discoveries in this exciting and rapidly developing field. We begin by discussing experimental advances in the generation and differentiation of pluripotent stem cells (PSCs), next moving to the maintenance of stem cells in different culture types, and finishing with a discussion of three-dimensional (3D) cell technology and future stem cell applications. Specifically, we highlight the following crucial domains: 1) sources of pluripotent cells; 2) next-generation in vivo direct reprogramming technology; 3) cell types derived from PSCs and the influence of genetic memory; 4) induction of pluripotency with genomic modifications; 5) construction of vectors with reprogramming factor combinations; 6) enhancing pluripotency with small molecules and genetic signaling pathways; 7) induction of cell reprogramming by RNA signaling; 8) induction and enhancement of pluripotency with chemicals; 9) maintenance of pluripotency and genomic stability in induced pluripotent stem cells (iPSCs); 10) feeder-free and xenon-free culture environments; 11) biomaterial applications in stem cell biology; 12) three-dimensional (3D) cell technology; 13) 3D bioprinting; 14) downstream stem cell applications; and 15) current ethical issues in stem cell and regenerative medicine. This review, encompassing the fundamental concepts of regenerative medicine, is intended to provide a comprehensive portrait of important progress in stem cell research and development. Innovative technologies and real-world applications are emphasized for readers interested in the exciting, promising, and challenging field of stem cells and those seeking guidance in planning future research direction.

Pulmonary Mycobacterium Spindle Cell Pseudotumor in Patient With Liver Transplant

We report a case of liver transplant patient who presented with lung masses, found to be Mycobacterium spindle cell pseudotumors. The masses demonstrated hypermetabolic activities on positron emission tomography. Core biopsy revealed sheets of spindle histiocytic cells with abundant acid-fast bacilli identified as Mycobacterium avium-intracellulare complex. This finding is a rare presentation of Mycobacterium infection, mainly nontuberculous Mycobaterium. It is characterized by a benign, spindle cell mass-forming reaction. Most of the reported cases had acquired immune deficiency syndrome or organ transplant. Histopathology illustrating the proliferation of spindle cell shaped histiocytes containing numerous acid-fast bacilli is the gold standard for diagnosis. The standard treatment has not been well established; previously reported cases followed the standard treatment for Mycobacterium based on organ involvement. Our case is the first case to our knowledge that reports pulmonary Mycobacterium spindle cell pseudotumors in a liver transplant recipient.

Antimycobacterial Susceptibility Testing of Nontuberculous Mycobacteria

Recommendations for first-line and second-line drug testing and organism group, specific methodologies, and reporting recommendations have been addressed by the Clinical and Laboratory Standards Institute (CLSI) and are important in the selection of appropriate antimicrobial treatment regimens for nontuberculous mycobacteria (NTM) disease. This review also includes recent information on new antimicrobials proposed for the treatment of NTM but not yet addressed by the CLSI and molecular (gene sequencing) methods associated with the detection of antimicrobial resistance of two major therapeutic antimicrobials, clarithromycin and amikacin.

Mycobacterial spindle cell pseudotumour: epidemiology and clinical outcomes

INTRODUCTION

Mycobacterial spindle cell pseudotumour (MSP) is a rare disease characterised by tumour-like local proliferation of spindle-shaped histiocytes containing acid-fast positive mycobacteria. The aim of this literature review is to describe the clinical parameters and treatment outcomes of patients with MSP.

METHODS

A literature search was conducted using the search terms related to mycobacteria and spindle cell tumours. A previously unreported stem cell transplant recipient from our institution diagnosed with MSP was also included. Demographics, comorbidities, site of infection, treatment and clinical outcomes were analysed.

RESULTS

Fifty-one patients were analysed. Twenty-six (51%) had HIV infection. Mycobacterium avium complex was the most frequent organism isolated in 24 (47.1%) followed by Mycobacterium tuberculosis complex in eight (16%) cases. Lymph nodes were the most common site of infection (45.1%). Twenty (39.2%) patients received antimycobacterial agents, 12 (23.5%) underwent surgical resection and six (11.8%) received antimycobacterial agents plus surgery. Treatment was successful in 24 (47.1%) patients and failed in 15 (29.4%); 13 of these 15 patients died. Antimycobacterial therapy was significantly associated with successful outcome compared with surgical resection or no treatment (P<0.001).

CONCLUSION

MSP is a rare condition associated primarily with immunodeficiencies. Antimycobacterial therapy is significantly associated with successful outcome.

Mycobacterium genavense infections in non-HIV immunocompromised hosts: a systematic review

BACKGROUND

Mycobacterium genavense is a non-tuberculous mycobacterium which can rarely cause disease in non-HIV immunocompromised hosts. We describe our experience with this unusual infection and perform a systematic review of the literature to describe the features of M. genavense infection in non-HIV immunocompromised hosts.

METHODS

All cases of Mycobacterium genavense infection in non-HIV patients at our institution were reviewed. In addition, we conducted a systematic review of the literature to identify previously published cases of M. genavense infections in non-HIV hosts.

FINDINGS

Two cases of M. genavense were identified at our center; a 51-year-old renal transplant recipient with a prosthetic knee joint infection and a 66-year-old woman with idiopathic CD4 lymphocytopenia with gastrointestinal tract disease. The systematic review identified 44 cases of M. genavense infection in non-HIV hosts. The most common underlying conditions were solid organ transplantation (40%), sarcoidosis (14%) and hematopoietic stem cell transplantation (7%). Disease most commonly involved the gastrointestinal tract, spleen, liver or bone marrow. Diagnosis was challenging with PCR required for identification in nearly all cases. Over one-third of patients died, which may reflect the combination of infection and underlying comorbidities. Overall cure was achieved in 61% with a mean duration of antimycobacterial therapy of 15.5 months (range 10-24).

CONCLUSION

M. genavense infection is a rare mycobacterial infection in non-HIV immunocompromised hosts. It should be suspected in immunocompromised patients presenting with disseminated mycobacterial infection, acid fast bacilli on smear or histopathologic examination, with poor or no growth in mycobacterial cultures.