Comments on: Dermatomyositis and Kaposi sarcoma

To the Editor

Alghanim and Gasmelseed postulate that dermatomyositis (DM) in the patient who later developed Kaposi’s sarcoma (KS) was a paraneoplastic syndrome.¹ We do not agree with their hypothesis.

Paraneoplastic syndromes are rare disorders that develop when T lymphocytes directed against antigens common to the tumor and normal cells attack normal tissues. The patient reported had lymphopenia prior to treatment. Furthermore, the patient developed KS one month after the diagnosis of DM and receiving one gram a day of methylprednisolone intravenously for 3 days, followed by 60-mg oral prednisolone daily. This treatment is enough to cause significant immunosuppression, weakening the immunological surveillance, allowing the reactivation of the latent human herpesvirus 8 infection. As a result, there is proliferation of the infected endothelial cells and the development of KS. One dose of 1 gm of methylprednisolone leads to selective T lymphocyte suppression 2 hours after each infusion, which is maximal at 6 hours with complete recovery 24 hour after each dose.² However, the 3 pulses of methylprednisolone were followed by daily doses of 60mg prednisolone, a large dose, thus maintaining the T lymphocyte suppression. The azathioprine has a lower onset of action and therefore its contribution is minimal in this patient.

There are many reports of patients developing KS after immunosuppressive therapy for DM and polymyositis but the interval in the current patient is one month which is the shortest but never the less, he has received intensive immunosuppression, has had pretreatment lymphopenia and is 73-years-old, older than the other patients reported.^3-7

Kaposi’s sarcoma should be considered in patients on immunosuppression if they develop a new rash.