Cutaneous lymphomas arise from a rare increase of T and B lymphocytes (white blood cells involved in fighting infections) which preferentially 'home' to the skin. The resulting disease could be one of a number of skin disorders that are fortunately rarely life threatening.

However, great anxiety can be associated with the diagnosis of these conditions; confusion with lymphomas primarily affecting internal organs and disease symptoms such as itching and ulceration can be unpleasant for patients.

Prior to development of modern techniques of studying cells in the body, skin lymphomas were described by a bewildering number of disease titles taken from the names of clinicians, Greek and Latin letters and even European cities!

The non-specialist may therefore only have a basic understanding of these diseases, particularly given that there are over 2,500 diseases described in the skin. Cutaneous T cell lymphomas (CTCL) generally appear as eczema-like skin rashes affecting widespread parts of the body whereas cutaneous B cell lymphomas (CBCL) generally produce skin lumps localised to one or two discrete areas.                          exceptional although lymph node disease occurs in some individuals.

Erythroderma (involvement of 90% or more of the body surface by inflammation) can develop in some patients with CTCL and requires treatment in hospital. This group of individuals have abnormal circulating lymphocytes in the blood which are generally not detected on blood counts and films except by sophisticated gene rearrangement techniques. They may also experience enlarged lymph nodes as a reactive response to skin inflammation.

If itching (pruritus) is severe, the patient may have circulating enlarged lymphocytes which are known as Sezary cells and have a characteristic appearance on blood films. These cells can increase dramatically in number with the passage of time and replace normal circulating T cells with consequent reduction of immunity to diseases such as chest infection. Patients who additionally have greatly enlarged lymph glands are diagnosed as having Sezary syndrome and can expect more severe symptoms than other patients with CTCL. Some patients who have CTCL have isolated lumps on their skin with behaviour more like CBCL; aggressive disease occurs only rarely in these cases.

Cutaneous B cell lymphomas

CBCL consist of a number of extranodal non-Hodgkin's lymphomas which occur in the skin. Although they are usually confined to the skin, systemic involvement (lymph nodes, bone marrow, peripheral blood and spleen) is more common than for CTCL. Skin lesions usually arise on normal skin of the head and neck, back or legs. They may be solitary, grouped or disseminated and have a deep red or purple appearance.

The clinical appearance is not usually distinctive and a skin biopsy is required for diagnosis and classification of the tumour type. If present, enlargement of lymph glands usually indicates active disease involvement rather than reaction to inflammation. CBCL's vary enormously in the aggressiveness of their behaviour, which can be predicted to some extent by the pathology of the tumour.

However, classification of CBCL is an evolving process and it has become recognised that B cell lymphomas which primarily develop in the skin behave less aggressively than tumours of similar appearance which originate internally.

Diagnosis and treatments

Cutaneous lymphomas are rare and patients will require referral to a hospital-based consultant dermatologist who will be best placed to make the diagnosis and to organise appropriate investigations and treatments. Individuals with mycosis fungoides will on occasion require radiotherapy but can generally be looked after in the skin department. Patients with CBCL are rarely diagnosed prior to biopsy and may therefore initially present themselves to a variety of clinical specialists.

The clinician taking primary responsibility for the patient's care here would depend on the type of lymphoma and extent of the disease. Patients should be offered early evaluation by an interested dermatologist and, ideally, their treatments managed by a multidisciplinary team involving haematologists, pathologists and oncologists (medical and radiotherapy) depending on local expertise and resources.

As indicated above, delays in diagnosis are not uncommon, particularly with CTCL. Development of sophisticated immunological and genetic analysis techniques are facilitating the complex interpretation of skin biopsies but are currently available in only a few research centres. Nodal biopsies are generally indicated only in the presence of enlarged glands.

Once a diagnosis is made, medical management will be dictated by the exact tumour type. Many people with CTCL of the mycosis fungoides type require only emollients and occasional use of potent topical corticosteroids ointment for patch disease.

The disease takes a chronic relapsing course. Widespread disease will frequently show response to ultraviolet A light treatment in combination with an oral light sensitiser (PUVA technique). PUVA is available in most skin departments in the UK.

Development of plaques can be managed in the same way as patch stage and results in frequent regression of lesions. Radiotherapy and topical nitrogen mustard may be required on occasion. These treatments are more commonly used for tumour stage of disease. Therapies such as total body superficial electron beam (using superficial X-ray treatment), oral chlorambucil and combination chemotherapy regimes are reserved for disease unresponsive to the above measures.

Patients with Sezary syndrome usually require more intensive therapies, including extra corporeal photo-chemotherapy (ECP) which is available only in a few specialised centres. This therapy involves irradiation of a portion of the patient's blood (whilst it is out of the body) with light, following photo-sensitisation with liquid psoralen. The blood is then returned to the body, and it appears that this treatment stimulates the immune system. Itching can be unbearable in this type of CTCL and challenging to treat. Infections are more common and require early treatment with antibiotics where appropriate.

Diagnosis of CBCL is usually made following surgical removal of a lump and delays are uncommon. However, diagnostic confusion may arise as many innocent injuries to the skin such as vaccinations and insect bite reactions can cause skin lesions which mimic CBCL clinically and on examination down the microscope (so called pseudolymphomas). Patients with true CBCL require staging investigations between 2-6 months after diagnosis.

Typically this would involve a bone marrow investigation, a CT scan of the abdomen and occasionally a lymph node biopsy to exclude systemic lymphoma. Treatment strategies are determined by whether the skin disease is primary or secondary.

Primary CBCL is generally successfully cured by surgical excision of lumps, localised radiotherapy or low toxicity chemotherapy regimes.

Systemic disease with secondary skin involvement will require management with radiotherapy or chemotherapy under the care of a consultant oncologist.

There is great interest among clinicians in establishing which methods of therapy are most effective for different patterns of disease. Clinical trials are difficult to organise owing to the relatively small numbers of patients affected by this group of disorders. However, a number of national and international study groups are currently working towards establishing multi-centre controlled trials with which to evaluate the efficacy of treatments.

Revised June 2004