What is benign lymphoplasmacytic plaque?
Benign lymphoplasmacytic plaque is a pseudolymphoma in children characterised by one or more chronic skin lesions, either solitary or in linear clusters, that have a characteristic polyclonal plasma cell infiltrate on histology. It was first described in 2009, with few reported cases so far.
Benign lymphoplasmacytic plaque has also been called cutaneous lymphoplasmacytic lymphoma and pretibial lymphoplasmacytic plaque.
Who gets benign lymphoplasmacytic plaque?
Benign lymphoplasmacytic plaque has mostly been reported to affect female children between the ages of 7 and 15 years. Isolated cases have been described in adult males over the age of 60. It seems to predominantly affect people of Caucasian descent, although cases have also been described in Japanese, African, and South Asian (Indian) children.
What causes benign lymphoplasmacytic plaque?
The cause of benign lymphoplasmacytic plaque is unknown. Preceding trauma to the affected area has been noted in a few cases, but no direct correlation has been confirmed.
What are the clinical features of benign lymphoplasmacytic plaque?
Benign lymphoplasmacytic plaque presents as a solitary chronic, persistent, and asymptomatic skin lesion that is resistant to topical and systemic treatment. Clusters of similar lesions often in a linear pattern may occur.
- The mean duration is 3 years.
- The lesion is a variable, reddish-brown, painless papule, or a scaly plaque.
- They most often affect the lower legs, but may also arise on the trunk, upper limbs, and buttocks.
- There are usually no other lesions elsewhere, and there are no systemic symptoms.
How is benign lymphoplasmacytic plaque diagnosed?
A skin biopsy is required as the diagnosis of benign lymphoplasmacytic plaque is made by dermatopathology and clinicopathologic correlation. The defining, compulsory histological findings are:
- Dense lymphoplasmacytic infiltrate
- The presence of large numbers of plasma cells
- The absence of clonality of plasma cells ie, polyclonal plasma cell infiltrate
- No atypical cells in the infiltrate.
Epithelioid granulomas may be seen.
Other tests should be performed to rule out infections, specifically atypical mycobacteria, leishmaniasis, borreliosis, syphilis, and fungal infections. The plasma cells must be tested for clonality to exclude the possibility of a lymphoproliferative disorder.
What is the differential diagnosis for benign lymphoplasmacytic plaque?
- Primary cutaneous plasmacytosis
- Acral lymphomatous angiokeratoma of children (APACHE)
- Infectious causes of cutaneous plasma cell infiltrates
- Plasma cell tumours such as lymphocytoma cutis
What is the treatment for benign lymphoplasmacytic plaque?
Benign lymphoplasmacytic plaque can be removed by surgical excision. Topical steroids and systemic steroids, intralesional steroid injection, partial removal by shave excision, and oral antibiotics have not proved successful.
What is the outcome for benign lymphoplasmacytic plaque?
It is uncertain how benign lymphoplasmacytic plaque progresses long term. Two cases persisting for ten years have been reported with no clinical changes. Spontaneous regression have not been reported.