Lymphomatoid Papulosis (LyP) is a chronic skin disease with characteristics of malignant T-cell lymphoma. Lymphomas originate in the lymph nodes present throughout the body and eventually spread to other organs, such as the liver, spleen and bone marrow. If untreated, lymphoma is generally progressive and fatal. LyP is not classified as a true lymphoma because the skin lesions appear then spontaneously regress in a cyclical fashion every few months.
In addition, LyP does not spread to other organs in the body and is not fatal. As such, LyP has been described as histologically malignant but clinically benign. This condition is also known as Macaulay’s disease, after the first clinician to use the term lymphomatoid papulosis.
LyP is one of several types of cutaneous T-cell lymphoproliferative disorders, which account for about 25% of cutaneous T-cell lymphomas. This disorder is rare, with a prevalence of only 1 to 2 cases per million people in the population. LyP occurs with equal frequency in men and women and with a peak incidence around 50 years of age.
The cause of LyP is essentially unknown. Several genetic defects have been noted in the cells of LyP lesions, but an agent causing these changes has not been identified. Clinicians still debate whether this disorder is simply a benign activation of T-lymphocytes in the skin or a true malignancy that remains confined to the skin and is inhibited from spreading by the patient’s immune system.
Signs and Symptoms of Lymphomatoid Papulosis
LyP is characterized by the recurrent appearance of small, raised skin lesions. The lesions are red to brown in color and may itch and bleed. They primarily occur on the trunk, arms, and legs in crops but may also occur on the palms, soles, face, and scalp. Very rarely, LyP lesions may be present in the mouth and throat. The lesions heal spontaneously within several weeks and leave a small, hypopigmented scar. This recurrence and regression may continue for years. Most patients do not complain of systemic symptoms, and laboratory abnormalities are generally not present.
Diagnosis and Staging
LyP should be diagnosed by skin biopsy. These biopsies should be obtained from at least two fully developed papules. Other conditions that may cause similar skin lesions and should be ruled-out include mycoses fungoides, cutaneous anaplastic large cell lymphoma, cutaneous Hodgkin’s disease, cutaneous leukemia, scabies, insect bites, and drug reactions. It must be stressed that a dermatopathologist experienced in the diagnosis of cutaneous lymphomas should review the biopsies to assure the correct diagnosis.
Once the diagnosis of LyP is confirmed, patients should undergo additional scans and tests to verify that indeed the disease is localized to the skin and is not a systemic lymphoma. This includes CT scans of the chest, abdomen, and pelvis, as well as complete blood count and serum chemistries. No formal staging system is used for LyP.
Although LyP itself is not a fatal disease, 10 to 20% of patients also develop an associated systemic lymphoma, typically anaplastic large cell, Hodgkinís disease, or mycoses fungoides. These cancers are much more aggressive and can be fatal. Monitoring of LyP patients at least twice a year is essential in order to detect malignant lymphomas at an early stage.
Unfortunately, no risk factors have been identified to determine which patients with LyP will go on to develop systemic lymphoma.
Because LyP is not a fatal disease, therapy is targeted at controlling the cyclical appearance of skin lesions and preventing local skin complications. Historically, patients received only topical treatment with corticosteroid creams or ointments to decrease the time to skin lesion resolution.
Currently, most clinicians opt for more aggressive treatments. One option often recommended is weekly oral low-dose methotrexate. Methotrexate is a chemotherapy drug that inhibits cell division by interfering with folate metabolism in cells.
This treatment is effective at resolving LyP lesions; however, the lesions generally return several weeks after stopping therapy. An aggressive topical therapy that is effective at controlling LyP lesions is oral psoralen plus ultraviolet light, so-called PUVA therapy. The oral psoralen inhibits DNA synthesis in the cells of skin lesions exposed to (activated by) the ultraviolet light.
Patients with refractory LyP or with contraindications to methotrexate or PUVA may be offered therapy with topical carmustine, topical nitrogen mustard, interferon injected into the lesions, low-dose oral cyclophosphamide or chlorambucil, or oral dapsone.
Supportive Care Issues
Oral methotrexate is generally well tolerated, but it can lead to blood count suppression and renal or liver damage. The drug is also contraindicated in women who are pregnant or wish to become pregnant and has multiple drug interactions that require close monitoring. PUVA theapy can lead to sunburns when higher doses are used. In addition, long-term use increases the risk of skin cancer.
Patients should be assured that LyP skin lesions are not contagious to others. When present, open skin lesions should be cleaned twice daily with mild soap and water, then covered with a topical antibiotic ointment such as bacitracin.
Any increase in redness or pain, or the presence of fever, may be indicative of a secondary skin infection and should be treated appropriately with oral antibiotics. Lesions that have crusted over may be covered loosely with bandages until healed. Patients should contact their physician if the lesions do not heal within 3 months of appearance.