From the Guidelines
Mycosis fungoides is the most common type of cutaneous T-cell lymphoma that typically presents with patches, plaques, or tumors on the skin, and its diagnosis requires a combination of clinical presentation, blood tests, and diagnostic criteria, including skin biopsy and immunophenotyping, as recommended by the most recent guidelines 1. The clinical presentation of mycosis fungoides often includes erythematous, scaly patches resembling eczema or psoriasis, commonly on sun-protected areas like the buttocks, trunk, and proximal extremities. As the disease progresses, these patches evolve into raised plaques and eventually tumors. Some key points to consider in the diagnosis of mycosis fungoides include:
- Blood tests for diagnosis include complete blood count with differential to assess for Sézary cells (atypical lymphocytes), comprehensive metabolic panel, lactate dehydrogenase (LDH) levels which may be elevated in advanced disease, and flow cytometry to identify abnormal T-cell populations, as suggested by 1 and 1.
- Definitive diagnosis requires skin biopsy showing characteristic histopathologic features including epidermotropism (migration of atypical T-cells into the epidermis), Pautrier microabscesses (collections of atypical lymphocytes in the epidermis), and band-like infiltrates of atypical lymphocytes with cerebriform nuclei in the upper dermis.
- Immunophenotyping typically reveals CD3+, CD4+, CD8-, CD45RO+ T-cells with loss of normal T-cell markers like CD7, as noted in 1 and 1.
- Multiple biopsies may be necessary as early-stage disease can be difficult to distinguish from benign inflammatory conditions.
- Additional staging workup may include CT scans, PET scans, and lymph node biopsies in advanced cases to determine disease extent, as recommended by 1 and 1. It is essential to follow the most recent guidelines for the diagnosis and management of mycosis fungoides, as outlined in 1, to ensure optimal patient outcomes.
From the Research
Clinical Presentation
- Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma, characterized by the evolution of patches, plaques, and tumors 2
- The disease has a protean clinical presentation in its early patch and plaque stages, making distinction from mimicking inflammatory dermatoses difficult 3
- MF is divided into 3 clinical phases: patch, plaque, and tumor stage, with a usually protracted clinical course over years or decades 2
- Variants of MF may present with unusual clinical features, such as hypopigmented, folliculotropic, pagetoid reticulosis, unilesional, granulomatous, and ichthyosis forms 4
Blood Tests and Diagnostic Criteria
- Diagnosis of MF requires a combination of clinical presentation, histopathology, and T-cell monoclonality detected by molecular studies 4
- Histopathologically, MF is characterized by an epidermotropic infiltrate of T lymphocytes that displays a helper phenotype in most cases 2
- Detection of atypical lymphocytes in the epidermis with minimal epidermal changes, basal alignment of lymphocytes along dermal-epidermal junction, and formation of Pautrier microabscesses are helpful histologic features in skin biopsies 3
- An aberrant immunophenotype of T cells and molecular detection of a clonal T-cell population can aid in diagnosis 3
- Confirmation of MF requires accurate assessment of symptoms and clinical signs, and subsequent correlation with dermatopathological findings 5
Diagnostic Challenges
- The subtlety of the initial clinical appearance of MF can result in diagnostic delays and hesitancy to refer suspected cases to specialist clinics 5
- Correct diagnosis of MF variants can be difficult due to their similarity to inflammatory skin diseases 6
- A comprehensive clinicopathologic correlation is essential to render the diagnosis of MF, and molecular studies can be highly sensitive and applicable to routinely processed skin biopsy specimens 4