What Is Cutaneous T-Cell Lymphoma?
With the continuous deepening of people's understanding of skin T-cell lymphoma, the correct classification of such complex and diverse disease lineages has become an important issue. The latest classification system combines the two classification methods of the World Health Organization (WHO) and the European Cancer Research and Treatment Organization (EORTC) based on the clinical manifestations of the disease, the morphology of tumor cells, and the biological characteristics of the cells. In 2005, A new classification of skin T-cell lymphoma (WHO-EORTC classification) is shown in Table 1. In the new classification, Sézary Syndrome, once classified as a subtype of MF, is separately classified into a new type. [1-2]
| Wang Yan | (Attending physician) | Department of Dermatology, Peking University First Hospital |
| Tuping | (Chief physician) | Department of Dermatology, Peking University First Hospital |
Skin T-cell lymphoma (CTCL) is a type of non-Hodgkin's lymphoma (NHL). It is caused by clonal hyperplasia of T lymphocytes. The disease is composed of a group of diseases with different clinical manifestations, histological characteristics, and prognosis. Skin T-cell lymphoma accounts for 75% -80% of all primary cutaneous lymphomas. In the past ten years, with the deepening of people's understanding of lymphoma, some new types have been discovered, and the classification of lymphoma has been continuously updated and improved. Compared with lymphomas in other parts, skin lesions of cutaneous lymphomas are easier to find and can be biopsied in time, which plays an important role in the diagnosis, classification and treatment of diseases.
- Western Medicine Name
- Cutaneous T-cell lymphoma
- English name
- cutaneous T-cell lymphoma, CTCL
- Affiliated Department
- Department of Physiology-Dermatology
- Main cause
- unknown
- Contagious
- Non-contagious
Skin T cell lymphoma disease classification
With the continuous deepening of people's understanding of skin T-cell lymphoma, the correct classification of such complex and diverse disease lineages has become an important issue. The latest classification system combines the two classification methods of the World Health Organization (WHO) and the European Cancer Research and Treatment Organization (EORTC) based on the clinical manifestations of the disease, the morphology of tumor cells, and the biological characteristics of the cells. In 2005, A new classification of skin T-cell lymphoma (WHO-EORTC classification) is shown in Table 1. In the new classification, Sézary Syndrome, once classified as a subtype of MF, is separately classified into a new type. [1-2]
Table 1. Classification of WHO-EORTC skin T-cell lymphoma in 2005
Mycosis fungoides |
Variant subtype of mycosis fungoides |
Hair follicular mycosis |
Paget-like reticulosis |
Granulomatous skin laxity |
Sézary syndrome |
Adult T-cell leukemia / lymphoma |
Primary skin CD30 + lymphocytic disease |
Primary skin gradual large cell lymphoma |
Lymphoma-like papulosis |
Subcutaneous panniculitis-like T-cell lymphoma |
Extranodal NK / T-cell lymphoma, nasal type |
Primary cutaneous peripheral T-cell lymphoma, unspecified |
Primary cutaneous aggressive epidermal CD8 + T-cell lymphoma * |
Skin / T-cell lymphoma * |
Primary skin CD4 + small / medium size pleomorphic T cell lymphoma * |
* Temporary classification |
Based on the above classification, WHO-EROTC further classifies cutaneous T-cell lymphomas into two categories: "inert" and "invasive" [2]. The incidence and 5-year survival rates of two types of skin T-cell lymphoma are shown in Table 2.
Table 2. Incidence and survival of cutaneous T-cell lymphoma
WHO-EORTC classification | Frequency of skin lymphoma (%) | 5-year survival rate (%) |
Biologically inert | | |
Mycosis fungoides | 54 | 88 |
Variant of mycosis fungoides | | |
Follicular follicular mycosis | 6 | 80 |
Paget-like reticulosis | 1 | 100 |
Granulomatous skin laxity | <1 | 100 |
Primary skin CD30 + lymphoproliferative disease | | |
Primary cutaneous anaplastic large cell lymphoma | 10 | 95 |
Lymphoma-like papulosis | 16 | 100 |
Subcutaneous panniculitis-like T-cell lymphoma | 1 | 82 |
Primary skin CD4 + small / medium pleomorphic T-cell lymphoma | 3 | 75 |
Invasive biological characteristics | | |
Sézary syndrome | 4 | twenty four |
Adult T-cell leukemia / lymphoma | Unclear | Unclear |
Extranodal NK / T-cell lymphoma, nasal type | 1 | <5 |
Primary skin aggressive epidermal CD8 + T-cell lymphoma | <1 | 18 |
Cutaneous / T cell lymphoma | 1 | <5 |
Primary cutaneous peripheral T-cell lymphoma, unspecified | 3 | 16 |
Pathogenesis
The pathogenesis of cutaneous T-cell lymphoma is currently unknown. Except for adult T-cell leukemia / lymphoma, which is considered to be related to human T-cell virus (HTLV), and extranodal NK / T-cell lymphoma, nasal type, which is considered to be related to Epstein-Barr virus (EBV), other types of skin T Cell lymphoma has not yet identified any relevant environmental factors. Immunological abnormalities, cytogenetic abnormalities, and cell resistance to apoptosis of skin homing T cells are important mechanisms of skin T cell lymphoma pathogenesis.
Diagnosis and treatment of cutaneous T-cell lymphoma
Histopathology
Patients suspected of having cutaneous T-cell lymphoma must first undergo a skin biopsy for a histopathological diagnosis to rule out benign lymphoproliferative disease. Some cutaneous T-cell lymphomas, such as mycosis fungoides, progress slowly and can be clinically and histologically without specific changes for many years. Therefore, if necessary, multiple points should be taken to obtain the most representative lesions.
Immunophenotype
Immunohistochemical examination using paraffin or frozen sections plays an extremely important role in the diagnosis and classification of lymphoma. The use of antigen-antibody reactions can distinguish the origin of tumor cells and play an important role in the classification of diseases.
3. T cell receptor gene rearrangement analysis
In recent years, T cell receptor (TCR) gene rearrangement analysis has become more and more widely used in the diagnosis and classification of lymphomas. Southern imprinting or PCR is currently commonly used. This method can identify whether the proliferating cells in the lesion are clonal T cells, which plays an important role in the diagnosis of benign and malignant diseases. However, the existence of clonal T cell subpopulations is not an absolute indicator for judging the benign and malignant nature of the disease, and comprehensive diagnosis should be combined with clinical manifestations and tissue manifestations to make a correct diagnosis.
4. Classification and staging
Once cutaneous T-cell lymphoma is diagnosed, its type must be identified. The diagnosis is based on clinical manifestations, histopathological manifestations, immunophenotypes, and T cell receptor gene rearrangement analysis. In addition, the correct staging method is needed to distinguish between skin T-cell lymphoma and affected systemic lymphoma. The staging method depends on the specific type of skin T-cell lymphoma. Routine analysis often involves a complete blood count, blood biochemistry, lymph node biopsy, bone marrow biopsy, and chest and abdominal CT.
