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Overlap connective tissue disease, pulmonary fibrosis, and extensive subcutaneous calcification
  1. A T Y Chan1,
  2. B P Wordsworth2,
  3. J McNally1
  1. 1Department of Rheumatology, Battle Hospital, Oxford Road, Reading RG30 1AG, UK
  2. 2Musculoskeletal Research Unit, Nuffield Orthopaedic Centre, Windmill Road, Headington, Oxford OX3 7LD, UK
  1. Correspondence to:
    Dr A T Y Chan;
    antonichan{at}hotmail.com

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Subcutaneous calcification is a common late feature of childhood dermatomyositis,1 but is rare as a presentation of adult onset dermatomyositis.2 It has been reported in scleroderma3 and systemic lupus erythematosus (SLE).4 However, extensive subcutaneous calcification in overlap connective tissue disease is rare.5 We describe two patients who had pulmonary fibrosis and extensive subcutaneous calcification of the buttocks in the same sequence as part of an overlap connective tissue disease.

CASE REPORTS

Case 1

A 28 year old woman presented in July 1994 with Gottron’s papules over the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints associated with muscle tenderness over her arms and thighs. In addition, she had a butterfly rash overlying her face, alopecia, oral ulcers, and Raynaud’s phenomenon. She also had arthritis of her PIP, knee, and ankle joints. Laboratory tests showed: haemoglobin 122 g/l; lymphopenia 0.77×109/l; erythrocyte sedimentation rate (ESR) 31 mm/1st h; C reactive protein (CRP) <6 mg/l; creatine kinase (CK) normal; antinuclear antibody 1/160 titre with a speckled pattern. Her other autoantibodies (anti-Jo-1, anti-Scl-70, anticentromere, anti-U1RNP, and double stranded DNA) were negative. Skin biopsy showed degeneration of the basal cell layer with vacuolar changes and a mononuclear cell infiltrate in the upper dermis. Electromyography of the deltoids showed low amplitude, short duration polyphasic potentials consistent with a myopathic process. A diagnosis of overlap connective tissue disease was made as the patient displayed features of both dermatomyositis and SLE.

A year later she developed shortness of breath, and a high resolution computed tomography (HRCT) scan of the lung disclosed basal fibrosis with areas of ground glass shadowing. Treatment was started with prednisolone 60 mg once a day, and her pulmonary function improved markedly.

In June 1999, five years after presentation, she complained of left buttock pain. Pelvic radiographs showed marked subcutaneous calcification around the left hip area (3×1 cm). This restricted movement around the left hip but was not severe enough to warrant surgical excision.

Case 2

A 35 year old man presented in October 1996 with a nine month history of arthralgia, alopecia, photosensitive rash, and Raynaud’s phenomenon. On examination he had arthritis of the MCP joints, wrists, shoulders, knees, and ankles. His hands had the typical appearance of scleroderma with nailfold infarcts and dilated capillary loops seen on capillaroscopy. Positive laboratory findings were as follows: haemoglobin 100 g/l; lymphopenia 0.8×109/l; ESR 62 mm/1st h; CRP <6 mg/l; CK normal; antinuclear antibody 1/320 titre with a homogenous pattern. His other autoantibodies (anti-Jo-1, anti-Scl-70, anticentromere, anti-U1RNP, and double stranded DNA antibodies) were negative. A diagnosis of overlap connective tissue disease was made as the patient displayed features of both SLE and scleroderma.

A year later he developed acute dyspnoea. An HRCT scan of the lung showed pulmonary fibrosis. Transbronchial biopsy revealed pulmonary fibrosis with a lymphocytic infiltrate. Prednisolone was started and he was also given intravenous cyclophosphamide.

In October 1999, three years after the initial presentation, he complained of left buttock pain. Examination showed a 10×8 cm solid mass in the left buttock, fixed to skin and muscle and tender to palpation (fig 1). This markedly limited movement in the left hip. These painful dystrophic calcifications were removed surgically, with a rapid and marked improvement in his symptoms and mobility.

Figure 1

Extensive subcutaneous calcification most marked around the left iliac wing

DISCUSSION

The pattern of pulmonary fibrosis and extensive subcutaneous buttock calcification in both our cases may be seen in overlap connective tissue disease. Itoh et al described a 38 year old woman with mixed connective tissue disease who had painful subcutaneous calcification in her buttocks, and pulmonary hypertension.6 The sequence of events and pattern of calcification were similar to our cases.

The predisposition to calcification in the buttock area may be due to local tissue damage and pressure necrosis. Dystrophic calcification occurs as a result of local tissue injury and inflammation. Tissue necrosis may increase alkalinity, which may cause calcium precipitation.5 Panniculitis, which occurs in connective tissue disease, is precipitated by local trauma to subcutaneous fat and leads to dystrophic calcification.7

Further studies are required to evaluate the use of medical treatments (diltiazem, warfarin, aluminium hydroxide, and colchicine) in subcutaneous calcification. We suggest that surgical excision be considered in patients with disabling extensive subcutaneous calcification (as in case 2).

REFERENCES

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