Mixed connective tissue disease
This is an overlap between SLE and either scleroderma or polymyositis.
As in LE, women are affected more often than men. Many develop swollen hands and sclerodactyly, and skin lesions like those of cutaneous LE may also be present. Alopecia is mild and the hair fall mimics telogen effluvium. Peri-ungual telangiectasia and pigmentary disturbances are common. About 25% of patients have a small vessel vasculitis with palpable purpura, leg ulcers and painful dermal nodules on the hands or elbows. Many show Raynaud’s phenomenon, arthritis, serositis and myositis. Headaches, weakness, fatigue, lymph node enlargement or hoarseness occur in about one in three patients; renal and central nervous system disease are less common.
The disorder is chronic, and usually turns into either SLE or systemic sclerosis.
The disorder can be confused with SLE, dermato-myositis, polymyositis, systemic sclerosis and other sclerosing processes such as porphyria cutanea tarda.
with mixed connective tissue disease have anti-bodies in high titre directed
against one or more extract-able nuclear antigens. These give a speckled
pattern when serum is reacted against nuclei and detected by indirect
immunofluorescence. Direct immunofluores-cence of involved and uninvolved skin
shows IgG within the epidermal nuclei, also in a speckled pat-tern. Only
one-third of patients have subepidermal immunoglobulin deposits in involved
skin. Most have hypergammaglobulinaemia, a high ESR, oesophageal dysmotility,
abnormal pulmonary function tests and a positive rheumatoid factor.
Hypocomplementaemia, leucopenia, anaemia, cryoglobulinaemia and false-positive
biological tests for syphilis occur in a few patients.
Treatment depends upon which organs are involved, but systemic steroids are usually needed, in the same dosage as for SLE. Immunosuppressive agents reduce the dosage of systemic steroids, and NSAIDs help with arthralgia, myalgia and swelling of the hands.