HTLV-I associated bronchioloalveolar disorder (HABA): disease concept and differential diagnosis of an unsolved disease entity

ABSTRACT

Introduction

Human T-cell leukemia virus type 1 (HTLV-I) associated bronchioloalveolar disorder (HABA) is a chronic and progressive bronchiolar/alveolar disorder related to HTLV-1 infection. Clinical knowledge and guidance are lacking for the diagnosis and management of this condition.

Areas covered

This work aimed to review the latest information and challenges regarding HABA diagnosis and treatment.

Expert opinion

HABA is an immune-mediated state induced by HTLV-1. For diagnosis of HABA, other infectious diseases and pulmonary infiltration of adult T-cell leukemia should be excluded by investigations such as computed tomography (CT), transbronchial biopsy, and bronchoalveolar lavage fluid (BALF) analysis. Typical CT findings in HABA include diffuse panbronchiolitis-like or bronchiectasis patterns, whereas cases with other abnormalities, including interstitial pneumonia, have also been reported. A high rate of polyclonal CD4+ and CD25+ lymphocytes is detected in BALF of patients with HABA, reflecting the infiltration of HTLV-1 infected T-cells in the lung. Current treatment options are not HABA specific, and include corticosteroids, macrolide antibiotics, and pirfenidone. Mitigation of the adverse effects of HTLV-1 infection requires the establishment of diagnostic criteria for the disease, screening programs for HABA in HTLV-1 infected individuals, and the development of effective disease treatment strategies.

KEYWORDS:

• BALF
• bronchiectasis
• HABA
• HAM/TSP
• HTLV-I
• panbronchiolitis

Article highlights

• Human T-cell leukemia virus type 1 (HTLV-1) infection has been identified as an adverse factor for overall survival.

• HTLV-1-associated bronchioloalveolar disorder (HABA) is an immune-mediated state induced by HTVL-1, and its pathophysiology is partly explained by the production of several pro-inflammatory cytokines/chemokines.

• Exclusion of opportunistic infections or adult T-cell leukemia (ATL) infiltration is required for the diagnosis of HABA.

• The radiological findings of HABA are diverse, and typically show panbronchiolitis or bronchiectasis patterns.

• Fluorescence-activated cell sorting (FACS) using bronchoalveolar lavage fluid samples could be a useful tool for distinguishing HABA from ATL. Without established treatment, treatments for HABA are based on background lung disease, irrespective of HTLV-1 infection.

Acknowledgments

We would like to thank Editage (www.editage.com) for English language editing.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or material discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or mending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.