Systemic Mycobacterium kansasii infection mimicking peripheral T‐cell lymphoma

Abstract

Nontuberculous mycobacteria are opportunistic pathogens which predominantly infect the immunocompromised host. The clinical and pathologic diagnosis of mycobacterial infection is generally not difficult. However, it may mimic malignancy on account of the clinical manifestations or the morphology of atypical lymphocytes with epithelioid histiocytes. The latter can be found in some types of lymphomas, especially T-cell lymphoma. This report describes two immunocompetent patients with systemic Mycobacterium kansasii infection presenting with fever, systemic lymphadenopathy, and osteolytic bone lesions. The microscopic features of these two cases were similar and were characterized by effacement of the nodal architecture by lymphocytic infiltrates and small aggregates of epithelioid histiocytes throughout. These lymphocytes showed mild atypia and expressed predominantly CD3. Bone marrow was also involved in the same process in one case and T-cell lymphoma with lymphoepithelioid features was the initial impression. However, further studies reported germline arrangements of T-cell receptor genes, presence of acid-fast bacilli, and recovery of M. kansasii in culture. At follow-up, the lymphadenopathy was seen to have disappeared during antimycobacterial treatment. This report describes two infectious cases with small aggregates of epithelioid histiocytes and atypical lymphocytes mimicking peripheral T-cell lymphoma; and such cases may become more common as the number of immunosuppressed hosts is increasing worldwide. We have reviewed the literature and summarized useful morphologic criteria for differentiation.

Autoantibody to Interferon-gamma Associated with Adult-Onset Immunodeficiency in Non-HIV Individuals in Northern Thailand

“…Opportunistic infections caused by intracellular organisms, including non-tuberculous mycobacteria (NTM), Cryptococcus neoformans , Penicillium marneffei, and non-typhoidal Salmonella spp., have been observed in non-HIV individuals in many countries [1]–[12]. In the largest case series of these patients, from Thailand, the authors could not identify the cause of impaired cell-mediated immunity [3].…”

Adult-Onset Immunodeficiency in Thailand and Taiwan

“…3,4 Since 2004, disseminated nontuberculous mycobacterial and other opportunistic infections involving neutralizing anti–interferon-γ autoantibodies have been described in 25 adults without human immunodeficiency virus (HIV) infection, most of whom were from East Asia. 5–13 In large case series from Thailand and Taiwan, descriptions of HIV-uninfected adults with disseminated mycobacterial infection (particularly with rapidly growing mycobacteria), often involving concomitant reactive dermatoses, 14–18 suggested a common syndrome of adult-onset immunodeficiency. To identify a defect that confers a predisposition to infections that are characteristic of advanced HIV infection, we analyzed humoral and cellular function, including assessment for anticytokine autoantibodies, in patients and healthy controls residing in regions where this syndrome appears to have a high prevalence…”

Peripheral T-cell lymphoma mimicking classic Hodgkin’s lymphoma in a patient presenting with fevers of unknown origin

“…Aetiologies in the literature reported to mimic PTCL include Hodgkin’s disease,10 cirrhosis and other hepatic diseases,11–13 cellulitis,14 stroke,15 ulcer,16 post-transplant lymphoproliferative disease (PTLD)17 and FUO18 (table 1). In addition, there are reports of PTCL having been diagnosed after initially mimicking alternate diagnoses, including Mycobacterium,19 EBV,20–22 natural killer lymphoma,23 tuberculosis24 and syphilis25 (table 2). With Hodgkin’s lymphoma in particular, Gaulard et al first noted the utility of combining histology and immunohistochemistry to reveal a clonal T-cell population to distinguish the aforementioned entities 26.…”