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Macrophagic myofasciitis is an emerging entity that was first reported in the Lancet in August 1998.1 Between May 1993 and 1999 more than 50 cases have been described in France.2 We report the first familial case of macrophagic myofasciitis.
A 45 year old woman was first admitted to hospital in July 1997 for pain and swelling of the right foot lasting for few months. Muscle biopsy of the right foot showed interstitial fibrosis with marked perivascular lymphocytes infiltrate. Only a few macrophages were seen but not in the subcutaneous tissue, epimysium, perimysium, and perifascicular endomysium. Periodic acid-Schiff (PAS) staining was negative. A diagnosis of focal myositis of the right foot was made3 and she received colchicine 1 mg daily. In November 1997 she was referred to our institution because her condition had not improved. At that time erythrocyte sedimentation rate (ESR), creatine kinase (CK), aldolase, and autoantibodies were normal or negative. Because focal myositis can evolve to polymyositis,4 an electromyography was performed showing a diffuse myopathic process. A muscle biopsy was performed in the deltoid but was normal. Myopathic electromyography was imputed to colchicine and this treatment was discontinued. A diagnosis of reflex sympathetic dystrophy of the right foot was proposed and calcitonin injections were started. In April 1998 the foot symptoms completely disappeared. In February 1999, diffuse myalgia appeared. Clinical examination was normal as were the laboratory and the second electromyography findings. However, a third muscle biopsy of the deltoid was performed and showed infiltration of the subcutaneous tissue, epimysium, perimysium, and perifascicular endomysium by sheets of non-epithelioid PAS-positive cells of macrophage lineage typical of macrophagic myofasciitis (fig1A).
In February 1999 her 11 year old son was referred to our institution for mild chronic myalgias and asthenia of two years' duration. Clinical examination was normal as were laboratory findings (including CK, aldolase, ESR) and electromyography. Nevertheless, in view of the mother's disease and despite the absence of objective signs, a left deltoid muscle biopsy was carried out. The findings were characteristic of macrophagic myofasciitis (fig 1B).
Our two cases of macrophagic myofasciitis underline the pitfalls of this diagnosis, especially the influence of the biopsy site for the demonstration of its typical pathological features. Owing to the rarity of macrophagic myofasciitis, the occurrence of the disease in the mother and her son is unlikely to be coincidental, and therefore probably reflects either a common genetic predisposition or the presence of the causative agent in the environment, or both. Of note is the fact that onset of clinical manifestations leading to the diagnosis of macrophagic myofasciitis occurred 24 and 18 months after immunisation against hepatitis B virus (HBV) (Genevac B, Pasteurs vaccins, Lyon, France and Engerix B, Smithkline Beecham, Nanterre, France) in mother and son, respectively. Additionally, both patients were vaccinated in the same side as the positive muscle biopsy (that is, the left deltoid) and a prior biopsy of the right deltoid of the mother was negative.
The putative role of the aluminic component of several vaccines—namely, those against HBV, has been recently suggested.5 If confirmed, this hypothesis should also consider the potential influence of the genetic background, as millions of French people have been recently immunised against HBV, whereas only a few dozen cases of macrophagic myofasciitis have been diagnosed. However, the possible role of currently unidentified environmental factors cannot be ruled out, given that macrophagic myofasciitis occurred concomitantly in our familial case report.
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