Human T-lymphotropic virus

Background

Single-stranded negative-sense RNA virus in the Retroviridae family, genus Deltaretrovirus
Four types:
- HTLV-1, cause of adult T-cell leukemia-lymphoma and HTLV-associated myelopathy
- HTLV-2, cause of HTLV-associated myelopathy
- HTLV-3 and HTLV-4 are rare

HTLV-1 endemic to central Africa, the Caribbean basin, parts of South America, and southwestern Japan
HTLV-2 endemic to indigenous people in the Americas, and Central African pygmies, as well as injection drug users in North America and Europe
Transmitted sexually, parenterally (blood-borne), and vertically (mother-to-child, primarily through breastfeeding)
Seroprevalence increases with age and is higher in women than men

Syndrome	HTLV-1	HTLV-2
Children
Infective dermatitis	yes	no
Lymphadenopathy	yes	yes
Adults
Adult T-cell leukemia-lymphoma	yes	no
HTLV-associated myelopathy	yes	yes
Infective dermatitis	yes	no
Polymyositis	possibly	unknown
Uveitis	yes	unknown
HTLV-associated arthritis	possibly	possibly
Sjögren syndrome	possibly	unknown
Strongyloidiasis	possibly	unknown
Pulmonary infiltrative pneumonitis	possibly	possibly
Invasive cervical cancer	possibly	unknown

Associated with HTLV-1, with a lifetime risk of 2 to 4% and latent period to 30 to 50 years
Aggressive T-cell leukemia or lymphoma with four subtypes
- Smoldering (5%), with ≥5% abnormal T-cells but otherwise normal differential, ± skin lesions ± pulmonary involvement
- Chronic (19%), with lymphocytosis ≥4 and T-cells >3.5, ± lymphadenopathy/organomegaly/skin lesions/pulmonary involvement
- Lymphoma/leukemia (19%), with lymphadenopathy without lymphocytosis; poor prognosis (median 10 months)
- Acute (57%), with increased leukemic T cells and worsening clinical picture including hypercalcemia; poor prognosis (median 6 months)
Presents with lymphadenopathy, hepatosplenomegaly, hypercalcemia, skin lesions, lytic bone lesions, and abnormal peripheral blood film with lymphocytosis and "flower cells"
Skin findings can be either localized or diffuse as papules, nodules, plaques, erythematous patches, and diffuse erythroderma

Also called tropical spastic paraparesis
Associated with HTLV-1 and -2, with lifetime prevalence of 4%
Thought to be caused by an autoimmune response from HTLV-1 antibodies due to molecular mimicry
Chronic progressive demyelinating disease affecting white matter and spinal cord
- Unexplained central neurological disease with loss of pyramidal tract
- Stiff gait progressing to spasticity and weakness, back pain, urinary incontinence, and impotence
- Can have parasthesias and burning sensation
- Impaired vibration sense
- Hyperreflexia with clonus and upgoing plantar reflexes
Usually insidious onset, but can be acute
MRI may be normal or show atrophy of the spinal cord and non-specific brain lesions
CSF can have mild lymphocytosis and mild protein elevation, including oligoclonal bands

Other neurological abnormalities, including sensory neuropathy, gait abnormality, bladder dysfunction, erectile dysfunction, amyotrophic lateral sclerosis, mild cognitive deficit, and motor neuropathy
Infective dermatitis, which occurs in children who experience failure to thrive, eczema, and Gram-positive infections
Polymyositis (HTLV-1-associated inflammatory myopathy of skeletal muscle)
Large joint polyarthropathy
Uveitis
Infiltrative pneumonitis
Chronic lympadenopathy
Increased infections:
- Strongyloides hyperinfection
- Crusted scabies
- Pneumocystis jirovecii
- Mycobacterium avium complex

Monitoring for signs or symptoms of leukemia, lymphoma, and neurological disease
Management of ATL per Hematologi-Oncology service