ICD-O-2 Morphology

9827/3: Adult T-cell leukemia/ lymphoma (HTLV-1 positive)
Effective 1992 - 2000

ICD-O-3 Morphology

9827/3: Adult T-cell leukemia/ lymphoma (HTLV-1 positive)
Effective 2001 and later


for cases diagnosed 1992 and later

Primary Site(s)

See Module 4: Rules PH7, PH8
Most common sites of involvement: skin, lung, liver, GI tract, CNS and bone marrow

Abstractor Notes

Adult T-cell leukemia/lymphoma (ATLL) has widespread lymph node and peripheral blood involvement. It is very rare for a patient to present with only bone marrow involvement.

Diagnostic Confirmation

This histology can be determined by positive histology (including peripheral blood) with or without genetics and/or immunophenotyping. Review the Definitive Diagnostic Methods, Immunophenotyping and Genetics Data sections below, and the instructions in the Hematopoietic Manual for further guidance on assigning Diagnostic confirmation.


Not Applicable

Module Rule

Module 4: PH7, PH8

Alternate Names

Adult T-cell leukemia/lymphoma (HTLV-1 positive)
Lymphomatous adult T-cell leukemia/lymphoma
Smoldering adult T-cell leukemia/lymphoma
T-cell lymphoma, small cell type, pleomorphic medium and large cell type (HTLV-1+)-Kiel


Adult T-cell leukemia/lymphoma (ATLL) is a mature T-cell neoplasm most often composed of highly pleomorphic lymphoid cells. The disease is usually widely disseminated and is caused by the human retrovirus HTLV-1. Most ATLL patients present with widespread lymph node involvement as well as involvement of peripheral blood. The histology shows remarkable pleomorphism, with several morphological variants having been described. The leukemic cells often show a multilobed appearance of so-called flower cells. Neoplastic cells show monoclonal integration of HTLV-1 and expression T-cell-associated antigens.

Several clinical variants of ATLL have been identified

1. The acute variant is most common and is characterized by a leukemic phase, often with a markedly elevated white blood cell count, skin rash, and generalized lymphadenopathy. Hypercalcemia, with or without lytic bone lesions, is a common feature. Patients with acute ATLL have systemic disease accompanied by hepatosplenomegaly, constitutional symptoms, and elevated lactate dehydrogenase (LDH). Cutaneous lesions are common.

2. The lymphomatous variant is characterized by prominent lymphadenopathy but without peripheral blood involvement. Most patients present with advanced stage disease similar to the acute form, although hypercalcemia is seen less often. Cutaneous lesions are common.

3. The chronic variant is frequently associated with an exfoliative skin rash. An absolute lymphocytosis may be present, but atypical lymphocytes are not numerous in the peripheral blood. Hypercalcemia is absent.

4. In the smoldering variant, the WBC count is normal with > 5% circulating neoplastic cells. ATLL cells are generally small, with a normal appearance. Patients frequently have skin or pulmonary lesions, but there is no hypercalcemia. Progression from the chronic or acute variant occurs in 25% of cases, usually after a long duration.

Definitive Diagnostic Methods

Bone marrow biopsy
Genetic testing
Histologic confirmation

Genetics Data

HTLV-1 monoclonal integration
TR genes are clonally rearranged


CCR4+ (expression/positive)
CD2+ (expression/positive)
CD3+ (expression/positive)
CD4+ (expression/positive)
CD5+ (expression/positive)
CD7- (no expression/negative)
CD8+ (expression/positive)
CD25+ (expression/positive)
FOXO3+ (expression/positive)


Radiation therapy

Transformations to

There are no known transformations

Transformations from

There are no known transformations

Corresponding ICD-9 Codes

204.8 Other lymphoid leukemia

Corresponding ICD-10 Codes

C91.5 Adult T-cell leukemia

Corresponding ICD-10-CM Codes (U.S. only)

C91.5 Adult T-cell lymphoma/leukemia (HTLV-1-associated) (effective October 01, 2015)

Signs and Symptoms

Elevated white blood cell count
Exfoliative skin rash
Skin or pulmonary lesions
Weight loss
Widespread lymph node involvement

Diagnostic Exams

Blood chemistry studies
CT (CAT) scan
Cytogenetic analysis
Flow cytometry
Lymph node biopsy
Peripheral blood smear
PET (positron emission tomography) scan

Progression and Transformation

Progression from the chronic or smoldering to the acute variant occurs in 25% of cases, but usually after a long duration.

Epidemiology and Mortality

Age: only in adults, 58 years median age
Country: Southwestern Japan, Caribbean, Central Africa
Sex: female predominance
Survival: 2 weeks to greater than 1 year depending on prognostic factors


Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds):
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition)
IARC: Lyon 2017
Section: Mature T- and NK-cell neoplasms
Pages: 363-367

International Classification of Diseases for Oncology, Third Edition, Second Revision. Geneva: World Health Organization, 2020.
Section: ICD-O-3.2 (2020) Morphological Codes