Mycosis fungoides

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Classification according to ICD-10
C84.0 Mycosis fungoides
ICD-10 online (WHO version 2019)

The Mycosis fungoides (MF) is a T cell - non-Hodgkin's lymphoma , predominantly the skin is concerned. The French doctors Jean-Louis-Marc Alibert and Pierre-Antoine-Ernest Bazin are considered to be the first to describe it in the first half of the 19th century. The disease is therefore also known as Alibert-Bazin syndrome . This designation is - like the older German name Wucherflechte - hardly in use.

Due to the skin appearances, the first writers believed that they were dealing with a fungal disease ( mycosis ) of the skin, hence the misleading name. So far, however, there is no reliable evidence that the disease is caused by infectious agents ( viruses , bacteria , fungi ).

The disease is caused by malignant ( CD4 positive ) T helper cells . Overall, it is a very rare disease (only 0.5% of all malignant lymphomas ), but MF is the most common form among the primary cutaneous T-cell lymphomas .

Epidemiology

Mycosis fungoides on the lip of a dog

Mycosis fungoides is the most common primary cutaneous lymphoma.

The disease mainly affects patients over 40 years of age (median 50-60 a), with men being affected twice as often as women.

It also occurs in animals (→ epitheliotropic T-cell lymphoma in dogs ). Dogs with atopic dermatitis are 12 times more likely to get it.

Stages and symptoms

  • Premycotic stage:

The premycotic stage is characterized by uncharacteristic rashes with persistent itching and possibly scaling v. a. on the trunk. The efflorescences can disappear and reappear in a different location. These eczema-like lesions can remain in this stage for years and then change into the infiltrative plaque stage. In the premycotic stage z. T. healings still possible.

  • Plaque stage:

At this stage there are often ring-shaped, plaque- like and slightly raised efflorescences , which can vary in severity.

  • Tumor stage:

At this stage, multiple, nodular and red-brownish tumor nodules develop in the skin area, often also in the face area (facies leonina, lion face). The nodes can ulcerate. In severe cases, erythroderma occurs . At this stage, the lymphoma usually spreads systemically.

  • Lymph node involvement:

At this stage multiple lymph nodes are involved.

  • Infestation of internal organs:

At an advanced stage , mycosis fungoides affects the liver , spleen , lungs and blood . The bone marrow is affected in about 30% of patients. The infestation of internal organs is prognostically unfavorable.

Tumor staging

The tumor staging according to the rules of the TNM system's. The AJCC (American Joint Cancer Committee) staging is also used clinically .

pathology

Histologically, polymorphic infiltrates can be detected in the affected skin areas, especially in the dermis . As the disease progresses, the actual neoplastic cells predominate in these infiltrates. These are predominantly small, have a cerebriform lobed cell nucleus and their immune phenotype corresponds to T helper cells. They show a marked epidermotropism, i. that is, they infiltrate the epidermis from the corium . In the higher layers of the epidermis (especially the stratum spinosum) they form so-called Pautrier microabscesses, that is, small focal tumor-cell islands. The affected skin also usually shows para- and orthokeratosis and irregular acanthosis . In the drainage area of ​​the skin lesions , lymph nodes can show what is known as dermatopathic lymphadenitis . Lymphoma cannot always be diagnosed with certainty in such altered lymph nodes.

In the stages localized on the skin, too, it has recently been possible to detect tumor cells in the bone marrow and lymph nodes using sensitive methods . The clinical significance of this fact is not entirely clear. In the plaque and tumor stage, tumor cells can be detected in the blood smear in up to 25% of patients .

No characteristic chromosomal changes are known. The molecular basis of epidermotropism has not yet been clarified. The tumor cells presumably express certain homing factors or are dependent on skin-specific growth factors. Normal T lymphocytes also sometimes show epidermotropism.

etiology

The etiology of the disease is unclear. However, there are different indications:

  • Viral hypothesis: There are other T-cell lymphomas associated with the HTLV-1 virus . This could not be shown in mycosis fungoides.
  • In some cases, type IV allergic reactions are found in patients. This suggests an increased activity of T helper cells.
  • Many patients were found to have increased exposure to chemicals. People who work in metalworking or in agriculture are at increased risk.
  • Chronic inflammation is said to lead to chronic stimulation and proliferation of T lymphocytes.

Diagnosis

The diagnosis is usually made by a biopsy from the affected areas of skin or tumorous lesions, in the generalized stages also from biopsies from lymph nodes, bone marrow and the affected organs. In the bone marrow, the infiltrates can be similar to B-CLL, but in contrast to B-CLL, the infiltrates are positive for acid phosphatase and acid naphthol acetate esterase. The leukemic Sézary syndrome can be diagnosed on the blood smear and immunophenotypic typing. The monoclonality of the tumor cells can be demonstrated by molecular biological investigations of the T cell receptor rearrangement.

Special forms

see also: Sézary syndrome

Sézary syndrome is a generalized, erythrodermic and leukemic variant of mycosis fungoides with a poor prognosis. In contrast to mycosis fungoides, the disease usually does not progress into the tumor stage, but rather the tumor cells (so-called Sézary or Lutzner cells) spread early and generalized through the blood and attack the bone marrow , lymph nodes and other organs. Sézary cells have the phenotype of mature T lymphocytes (CD 4 positive, CD5 positive) and are characterized by their typical cerebriform nucleus. These cells are also found in the tissue infiltrates of the mycosis fungoides. The Sézary syndrome is treated therapeutically like mycosis fungoides.

Differential diagnosis

In the premycotic stage, mycosis fungoides should be differentiated from primary, eczematous skin diseases (e.g. atopic eczema , psoriasis )

therapy

Stage-appropriate

Stage 1:

  • Excision in the healthy
  • Photochemotherapy with psoralen and UV treatment ( PUVA )

Stage 2:

Stage 3:

General measures:

  • Treatment of itching (pruritus)

forecast

In stage I, the disease can linger or be cured for years . Otherwise, mycosis fungoides is considered an incurable disease. Sézary syndrome has a poor prognosis. A disease with tumor cells with the immune phenotype of T suppressor cells (CD 8 positive) does not seem to have any prognostic effect.

Complications

  • Transition to a highly malignant T-cell lymphoma (large-cell T-cell lymphoma)
  • Involvement of internal organs
  • functional immunosuppression (probably due to factors secreted by the lymphoma)

literature

Individual evidence
  1. ↑ Schwarz, Thomas .: Dermatology Venerology: Basics. Clinic. Atlas . 3rd completely revised edition. Berlin, Heidelberg 2018, ISBN 978-3-662-53647-6 .
  2. ↑ D. Santoro et al .: Investigation on the association between atopic dermatitis and the development of mycosis fungoides in dogs: a retrospective case-control study. In: Veterinary Dermatology 18 (2007), pp. 101-106.
  3. ↑ Hafeez Diwan, Doina Ivan: CD8-positive mycosis fungoides and primary cutaneous aggressive epidermotropic CD8-positive cytotoxic T-cell lymphoma . In: Journal of Cutaneous Pathology . tape 36 , no. 3 , March 1, 2009, ISSN  1600-0560 , p. 390–392 , doi : 10.1111 / j.1600-0560.2008.01259.x .

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