Diagnosis of cutaneous mycobacterial spindle cell pseudotumor in the absence of typical inflammatory cells: A case report.

Mycobacterial spindle cell pseudotumor (MSP) is a non-neoplastic condition that is characterized by spindle-shaped histiocytes colonized by mycobacteria. MSP is most commonly diagnosed in the immunocompromised and, while MSP can occur throughout the body, the most common sites of MSP involvement are the lymph nodes and the skin. To diagnose MSP, histopathological analysis typically demonstrates the presence of inflammatory cells, in addition to spindle cells and the unequivocal mycobacteria, which guides the diagnosis away from potential neoplasms. If properly diagnosed and treated with appropriate antibiotic therapy, patients tend to experience almost complete resolution of their symptoms. MSP is a rare condition; to our knowledge, there have only been 11 documented cases of cutaneous MSP, including the one introduced in this report. Here, we present a unique case of a 50-year-old female on chronic immunosuppressive therapy diagnosed with cutaneous MSP in the absence of inflammatory cells on pathology.

The Pathology of Lymphocytes, Histiocytes, and Immune Mechanisms in Mycobacterium tuberculosis Granulomas.

Granuloma formation is the pathologic hallmark of tuberculosis (TB). Few studies have detailed the exact production of cytokines in human granulomatous inflammation and little is known about accessory molecule expressions in tuberculous granulomas. We aimed to identify some of the components of the immune response in granulomas in HIV-positive and -negative lymph nodes. We investigated the immunohistochemical profiles of CD4+, CD8+, CD68+, Th-17, Forkhead box P3 (FOXP3) cells, accessory molecule expression (human leukocyte antigen [HLA] classes I and II), and selected cytokines (interleukins 2, 4, and 6 and interferon-γ) of various cells, in granulomas within lymph nodes from 10 HIV-negative (-) and 10 HIV-positive (+) cases. CD4+ lymphocyte numbers were retained in HIV- granulomas, whereas CD4+:CD8 + cell were reversed in HIV+ TB granulomas. CD68 stained all histiocytes. Granulomas from the HIV+ group demonstrated a significant increase in FOXP3 cells. Interleukin-2 cytoplasmic expression was similar in both groups. Interferon-gamma (IFN-γ) expression was moderately increased, IL-6 was statistically increased and IL-4 expression was marginally lower in cells from HIV- than HIV+ TB granulomas. Greater numbers of cells expressed IFN-γ and IL-6 than IL-2 and IL-4 in HIV- TB granulomas. This study highlights the varied cytokine production in HIV-positive and -negative TB granulomas and indicates the need to identify localized tissue factors that play a role in mounting an adequate immune response required to halt infection. Although TB mono-infection causes variation in cell marker expression and cytokines in granulomas, alterations in TB and HIV coinfection are greater, pointing toward evolution of microorganism synergism.

Hansen's disease with lepra reaction presenting with IgA dominant infection related glomerulonephritis.

Various renal abnormalities in leprosy have been described largely in literature but the occurrence of IgA dominant infection related glomerulonephritis in leprosy with type 2 lepra reaction has not been reported so far. We present here a 60-year-old man with a history of leprosy in the past admitted with type 2 lepra reaction, rapidly progressive glomerulonephritis with severe renal failure requiring dialysis and diagnosed to have IgA dominant infection related glomerulonephritis.

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

We describe the first reported pediatric patient to our knowledge with a spindle cell pseudotumor caused by Mycobacterium genavense in a hematopoietic stem cell transplant recipient, and review the literature of such an entity in the transplant population.

Unsolved matters in leprosy: a descriptive review and call for further research.

Leprosy, a chronic mycobacterial infection caused by Mycobacterium leprae, is an infectious disease that has ravaged human societies throughout millennia. This ancestral pathogen causes disfiguring cutaneous lesions, peripheral nerve injury, ostearticular deformity, limb loss and dysfunction, blindness and stigma. Despite ongoing efforts in interrupting leprosy transmission, large numbers of new cases are persistently identified in many endemic areas. Moreover, at the time of diagnosis, most newly identified cases have considerable neurologic disability. Many challenges remain in our understanding of the epidemiology of leprosy including: (a) the precise mode and route of transmission; (b) the socioeconomic, environmental, and behavioral factors that promote its transmission; and

Cellular Microbiology of Mycoplasma canis.

Mycoplasma canis can infect many mammalian hosts but is best known as a commensal or opportunistic pathogen of dogs. The unexpected presence of M. canis in brains of dogs with idiopathic meningoencephalitis prompted new in vitro studies to help fill the void of basic knowledge about the organism's candidate virulence factors, the host responses that it elicits, and its potential roles in pathogenesis. Secretion of reactive oxygen species and sialidase varied quantitatively (P < 0.01) among strains of M. canis isolated from canine brain tissue or mucosal surfaces. All strains colonized the surface of canine MDCK epithelial and DH82 histiocyte cells and murine C8-D1A astrocytes. Transit through MDCK and DH82 cells was demonstrated by gentamicin protection assays and three-dimensional immunofluorescence imaging. Strains further varied (P < 0.01) in the extents to which they influenced the secretion of tumor necrosis factor alpha (TNF-α) and the neuroendocrine regulatory peptide endothelin-1 by DH82 cells. Inoculation with M. canis also decreased major histocompatibility complex class II (MHC-II) antigen expression by DH82 cells (P < 0.01), while secretion of gamma interferon (IFN-γ), interleukin-6 (IL-6), interleukin-10 (IL-10), and complement factor H was unaffected. The basis for differences in the responses elicited by these strains was not obvious in their genome sequences. No acute cytopathic effects on any homogeneous cell line, or consistent patterns of M. canis polyvalent antigen distribution in canine meningoencephalitis case brain tissues, were apparent. Thus, while it is not likely a primary neuropathogen, M. canis has the capacity to influence meningoencephalitis through complex interactions within the multicellular and neurochemical in vivo milieu.

Late recurrent testicular seminoma: histological evidence is required.

INTRODUCTION: Over the past 3 decades, the appropriate management of metastatic germ cell tumours (GCT) has been defined by several phase III trials. Many follow-up recommendations have been published based on expert consensus. However, common clinical scenarios can still be vexing for clinicians who are less experienced at managing patients with testicular cancer. CASE REPORT: We highlight the arduous diagnostic work-up of a suspected late relapsing metastatic GCT in a patient suffering from fatigue, weight loss and prominent retroperitoneal lymph nodes, 4 years after first-line chemotherapy for metastatic seminoma. The various explorations finally led to the diagnosis of Whipple's disease. CONCLUSION: This unusual clinical case strongly highlights the need to perform an exhaustive evaluation, with a biopsy, if a late recurrent GCT is suspected to avoid pointless and potentially harmful treatment.

Visibility of Histoplasma within histiocytes on hematoxylin and eosin distinguishes disseminated histoplasmosis from other forms of pulmonary histoplasmosis.

The visibility of Histoplasma within histiocytes on hematoxylin and eosin is a well-known feature of disseminated histoplasmosis. However, it is unclear whether this finding can be used to differentiate disseminated histoplasmosis involving the lung from other forms of pulmonary histoplasmosis. The aim of this study was to determine whether the visibility of Histoplasma within histiocytes on hematoxylin and eosin in lung biopsies suggests disseminated disease. Lung biopsies in which Histoplasma was identified were re-examined to determine whether organisms were visible within histiocytes on hematoxylin and eosin. Clinical findings were reviewed retrospectively to determine the type of histoplasmosis. Histoplasma was visible within histiocytes on hematoxylin and eosin in lung biopsies from 4 patients (2 men, 2 women, 50-74 years) who presented with pulmonary manifestations without definite evidence of disseminated disease at the time of biopsy. Subsequently, all 4 manifested clinical and/or microbiologic features of disseminated disease (positive extrapulmonary cultures and fatal outcome in 2, positive extrapulmonary cultures in 1, and multiorgan failure and fatal outcome in 1). In contrast, organisms were identified on silver stains but could not be visualized on hematoxylin and eosin in 42 patients, none of whom showed clinical or microbiologic evidence of disseminated disease (pulmonary histoplasmoma, 38; acute pulmonary histoplasmosis, 4). In lung biopsies, the visibility of Histoplasma within histiocytes on hematoxylin and eosin suggests disseminated disease. Recognition of the significance of this finding is helpful in diagnosing disseminated disease in patients who present primarily with pulmonary manifestations without definite clinical evidence of dissemination at the time of biopsy.

Cytological diagnosis of paracoccidioidomycosis: a report of four cases.

Paracoccidioidomycosis (PCM) is a common deep mycosis in South America caused by Paracoccidioides brasiliensis, a dimorphic fungus. Biopsy is the most frequent diagnostic method. The aim of this article is reporting four cases of PCM, in which intraoral involvement simulated squamous-cell carcinoma and was diagnosed by exfoliative cytology. We highlight this diagnostic tool as a simple, low cost, painless, noninvasive, and fast diagnostic method for PCM.

Mycobacterial spindle cell pseudotumor of the lung.

Mycobacterial spindle cell pseudotumor (MSP) is a rare benign lesion characterized by local proliferation of spindle-shaped histiocytes containing acid-fast mycobacteria. Most reported cases of MSP occur in the lymph nodes, skin, spleen, and brain in patients who are immunocompromised, particularly following solid organ transplant and in those with AIDS. This is a case report of a patient with AIDS who presented with cough, generalized weakness, and fatigue, who was found to have multilobar lung masses that were MSP, which to our knowledge has not yet been reported in the literature.

Biochemical and pathophysiological characterization of Helicobacter pylori asparaginase.

Asparaginase was purified from Helicobacter pylori 26695 and its pathophysiological role explored. The K(m) value of asparagine was 9.75 ± 1.81 µM at pH 7.0, and the optimum pH range was broad and around a neutral pH. H. pylori asparaginase converted extracellular asparagine to aspartate. H. pylori cells were unable to take up extracellular asparagine directly. Instead, aspartate produced by the action of the asparaginase was transported into H. pylori cells, where it was partially converted to ß-alanine. Asparaginase exhibited striking cytotoxic activity against histiocytic lymphoma cell line U937 cells via asparagine deprivation. The cytotoxic activity of live H. pylori cells against U937 cells was significantly diminished by deletion of the asparaginase gene, indicating that asparaginase functions as a cytotoxic agent of the bacterium. The cytotoxic effect was negligible for gastric epithelial cell line AGS cells, suggesting that the effect differs across host cell types. An asparaginase-deficient mutant strain was significantly less capable of colonizing Mongolian gerbils. Since asparagine depletion by exogenous asparaginase has been shown to suppress lymphocyte proliferation in vivo, the present results suggest that H. pylori asparaginase may be involved in inhibition of normal lymphocyte function at the gastric niche, allowing H. pylori to evade the host immune system.

Disseminated Mycobacterium genavense infection in a healthy boy.

Mycobacterium genavense (M genavense) has been recognized as a life-threatening pathogen in severely immunocompromised patients. To our knowledge, disseminated M genavense infection has never been described in immunocompetent individuals. Here, we report a case of disseminated M genavense infection in a healthy Japanese boy. A 15-year-old boy who had never been diagnosed with an immunodeficiency disorder was hospitalized because of ileus. Tumorous lesions were identified in the ileum, cecum, and ascending colon, resulting in stenosis of ileocecal valve. There was diffuse proliferation of histiocytes throughout the intestinal wall, along with lymphocytic infiltration. No nuclear or cellular atypia was present in these cells. Ziehl-Neelsen staining revealed numerous acid-fast bacteria in histiocytes. After surgery, systemic lymph node swelling was noticed by generalized examination, including the mesenteric and cervical lymph nodes. M genavense DNA was identified by direct sequencing of 16S ribosomal DNA that had been amplified by polymerase chain reaction.

Mycobacterium microti infection associated with spindle cell pseudotumour and hypercalcaemia: a possible link with an infected alpaca.

A 44-year-old woman who had recently been on immunosuppressive therapy presented with malaise, cough, fever, weight loss, lymphadenopathy, severe hypercalcaemia and a paratracheal mass on imaging. The initial impression was of disseminated malignancy, and lymphoma was suspected. A mediastinal biopsy showed a mycobacterial spindle cell pseudotumour containing acid and alcohol fast bacilli (AAFB). Sputum microscopy demonstrated AAFBs, confirmed as Mycobacterium tuberculosis complex by PCR. Prolonged culture grew Mycobacterium microti, an organism often associated with disease in small rodents and llamas. M microti isolates from postmortem samples of an alpaca at a nearby farm were genetically indistinguishable. Although the patient had not visited the farm, concurrent illness in her adopted stray cat suggested a possible zoonotic connection. The patient responded to antituberculous therapy, and rehydration and pamidronate for hypercalcaemia. We believe the hypercalcaemia was caused by a similar mechanism to raised calcium levels sometimes seen in tuberculosis.