Introduction
The termĀ overlap syndrome includes a large group of conditions
characterized by the coexistence of signs, symptoms, and immunological
features of two or more connective tissue diseases occurring
simultaneously in the same patient.1 It is very rare to see an overlap
of inflammatory myositis and SLE and it has not been well
studied.2 With variable epidemiological data, most
often diagnosed concurrently with SLE.3 In contrast to
myalgia which can affect nearly half of patients with SLE, true myositis
is relatively rare as shown by some studies.11Myositis can occur before, after SLE, or sporadically both diseases can
be present simultaneously.10
Myositis associated with overlap syndromes is usually of paroxysmal
variety and has been associated with one or another of connective tissue
disorders.1 Raised serum creatine kinase is found to
correspond with underlying myositis in patients with
SLE.12 Furthermore, the presence of myositis-specific
antibodies such as anti-U1RNP, anti-Ro/SSA, anti-La/SSB, anti-Sm or
anti-PM-Scl is suggestive of an overlap
myositis.13,12