Leukaemia cutis is a rare condition in which leukaemia cells are found in the skin tissue. This infiltration of the skin causes visible patches or lesions to appear which can be a distinctive sign of a person having leukaemia.
How these lesions look varies from one case to another, ranging anywhere from; flesh-to red-to purple coloured papules, raised flattened areas known as plaques or small nodules. Patients with leukaemia cutis may have a single lesion or multiple effected areas.
The most common region to be affected is the legs, followed by arms, back, chest, scalp, and face.
Leukaemia cutis is very rare, occurring in only about 3% of total cases of leukaemia. With this in mind, it is unsurprising that most lesions seen in leukaemia patients are not leukaemia cutis. In fact, most lesions (40%) seen in leukaemia patients are caused by other complications of leukaemia. Different types of bruising (petechiae, purpura, ecchymoses) or infections such as thrush or herpes are more likely to be responsible for lesions in these patients. The toxicity of some of the treatments for leukaemia themselves can also sometimes cause lesions (e.g chemotherapy).
In the rare occasion that leukaemia cutis occurs, the patient will normally have already been diagnosed with leukaemia. However, in 7% of cases of leukaemia cutis, the skin lesion is the very first symptom of a blood cancer. This is sometimes referred to as “aleukaemic leukaemia cutis”.
Frequency across the different types of leukaemia
Leukaemia cutis can occur in males and females of any age and it has been noted in almost every kind of leukaemia. Because leukaemia cutis is such a rare condition, but also develops across quite a wide range of possible types of leukaemia, the exact incidence of leukaemia cutis is not certain. Nonetheless, leukaemia cutis is known to most commonly occur in people with Acute myeloid leukaemia (AML), and is apparent in approximately 10-15% of cases overall. Certain subtypes of AML carry a greater risk. For example, these skin lesions can be seen in 50% of people with a certain type of AML called acute myelomonocytic leukaemia (AMMoL).
Leukaemia cutis is least likely to occur in chronic types of leukaemia. For example, it is only seen in around 4% of people with chronic lymphocytic leukaemia (CLL). Unfortunately, when skin involvement is observed in CLL, it often indicates disease progression and it can sometimes be a sign of Richter’s Syndrome (RS), a rare complication of CLL in which the cancer transforms to become more aggressive. Reports of leukaemia cutis being the first symptom of CLL are highly unusual, but it is still possible.
Leukaemia cutis as a primary symptom of leukaemia
“Aleukaemic leukaemia cutis” refers to the 7% of cases whereby leukaemia cutis is seen as the first symptom of leukaemia, before a diagnosis has been made. In these cases, the dermatologist (after inspecting a skin biopsy) will often be the most instrumental in the diagnosis procedure. Accurate early diagnosis can have a huge impact on the prognosis or outcome for these patients, as aleukaemic leukaemia cutis can be a vital warning sign of leukaemia and more serious problems to come. In the rare case of aleukaemic leukaemia cutis, lesions can come months or even years before the leukaemia is detectable in the bone marrow, and before other more common symptoms have occurred. The early recognition of leukaemia cutis lesions is therefore very important to improve patient outcomes in this small subset of patients.
Congenital Leukaemia Cutis
Congenital leukaemia refers to any leukaemia that is present at birth or occurs in infants before 6 weeks of age. Although leukaemia is considered the most common childhood cancer, congenital leukaemia is extremely rare, accounting for less than 1% of all cases of childhood leukaemia’s.
The frequency of leukaemia cutis appears to be much more common among this patient group than in adults, being evident in as many as 30% of infants with congenital leukaemia.
Again, sometimes leukaemia cutis can be a presenting symptom of congenital leukaemia in infants. This is one of the most common causes of the “blueberry muffin syndrome” in new born babies (a term used to describe an infant that is born with lots of dark blue/purple patches on the skin). hepatosplenomegaly (enlarged spleen) is often another telling sign of leukaemia in these infants.
Treatment of leukaemia cutis
Leukaemia cutis is a local indication of an underlying leukaemia. Therefore, localised therapies such as surgery or radiation are not usually recommended for use on their own because simply removing the lesions from the skin will not get rid of the underlying problem. Since all patients that present with leukaemia cutis go onto to develop leukaemia (regardless of whether other symptoms are already present), systemic chemotherapy (throughout whole body) is the most common choice of treatment, to eradicate the leukaemia cells or to prevent it from developing.
Localised radiation, electron beam therapy, surgery or phototherapy may be conducted alongside chemotherapy to help remove the lesions from the affected areas of the skin.
The use of local radiotherapy as well as chemotherapy can sometimes cause soars and burns to the skin. Topical steroids, mentholated lotions or topical lidocaine preparations can be helpful to relieve these symptoms.
Moisturisers such as Biafine can help speed up the healing process of the skin after radiation damage.
Most patients will also receive antimicrobials as a preventative measure against infections after these skin lesions are found. Blood cancer patients with open wounds are more prone to infectious agents such as herpes simplex virus (HSV) or candida species (cause of thrush).