What are the expected findings in Mycosis Fungoides (Cutaneous T-Cell Lymphoma) investigations?

From the Guidelines

The expected findings in Mycosis Fungoides (Cutaneous T-Cell Lymphoma) investigations typically include skin lesions, lymphadenopathy, and abnormal blood tests.

Key Findings

• Skin biopsy is essential for diagnosis, with routine histology and immunophenotyping, and evaluation for clonality of TCR gene rearrangement (optional) 1
• Blood tests may show abnormal lymphocytes, including Sézary cells, and elevated LDH levels 1
• Radiological tests, such as CT scans, may reveal lymphadenopathy or organomegaly 1
• Lymph node biopsy may be necessary to confirm lymph node involvement, with excisional biopsy and routine histology, immunohistochemistry, and TCR gene rearrangement analysis 1

Diagnostic Criteria

• The diagnosis of Mycosis Fungoides is based on a combination of clinical, histological, and immunophenotypic findings, including the presence of atypical T-cells in the skin and blood 1
• The revised TNMB staging system is used to classify the disease, with stages ranging from IA to IVB 1

Prognostic Factors

• Older age, large cell transformation, and elevated LDH values are independent unfavorable prognostic factors in Mycosis Fungoides 1
• The presence of Sézary cells in the blood and lymph node involvement are also associated with a poorer prognosis 1

From the Research

Expected Findings in Mycosis Fungoides Investigations

• Clinical presentation: Mycosis fungoides (MF) typically presents with patches, plaques, tumors, or erythroderma, with a wide range of dermatological manifestations 2, 3
• Histopathological findings: Epidermotropism is the histopathologic hallmark of the disease, with neoplastic T cells localizing to the skin 4, 3
• Immunohistochemical analysis: Essential to confirm the diagnosis of MF, with the use of immunophenotyping and polymerase chain reaction to improve diagnostic accuracy 4, 5
• Molecular biology: Molecular biology tools, such as T-cell clonality testing, can aid in establishing a diagnosis of MF 5, 6
• Staging: The TNMB system is used for staging, with factors such as the extent and nature of skin involvement, extracutaneous disease, blood involvement, age, and lactate dehydrogenase elevation influencing prognosis 2, 5
• Prognosis: Independent prognostic factors include the extent and nature of skin involvement, the presence of extracutaneous disease, blood involvement, age > or = 60 years, and lactate dehydrogenase elevation, with median survival ranging from 0.9 to 11 years depending on the stage 2, 5

Diagnostic Challenges

• MF can mimic a wide variety of skin diseases, making diagnosis difficult due to highly variable presentations and nonspecific histological findings 4, 3
• Atypical types of MF can simulate benign inflammatory skin disorders, either clinically, histopathologically, or both 3
• Differential diagnosis is crucial to distinguish MF from histopathologic mimics, with the use of ancillary testing and clinical experience 4, 6