Calcinosis with sinuses caused by dermatomyositis

Introduction

Dermatomyositis (DM) is an inflammatory myopathy of unknown cause which affects the skeletal muscles. DM is a rare disease, and the complication of calcinosis is even rarer. In this study, a case of calcinosis with sinuses caused by DM is reported, and the epidemiology, diagnosis, and treatment of calcinosis caused by DM were analyzed.

Case report

A 34‐year‐old woman was admitted to hospital on September 14, 2009 for repeated defects in the skin of her right buttock, which had been secreting a golden, sand‐like material for six months. An area of skin pigmentation (6 cm × 7 cm in area) was found over the right buttock, and within it there was a round sinus (1 cm × 1 cm in size) which was secreting a golden, sand‐like material (Fig. 1). There was pain in the area around the sinus, and the muscles of the right buttock were weak. The skin of the anterior lower abdomen and both buttocks was hard and inflexible. There was no tenderness in the area of skin pigmentation, and the skin temperature was normal. No limitation of movement in the lower limbs was found. The patient had a history of a diagnosis of DM having been made in 2001. At that time, swelling and erythema had been present in the right buttock. These symptoms resolved after treatment with topical and oral corticosteroids, so drug therapy had been stopped. There had been no recurrence until 2009. Six months prior to the current presentation, the skin in the right buttock had ruptured twice, and failed to heal, eventually forming a purulent mass.

Figure 1.

The preoperative condition of the soft tissue: Skin pigmentation (6 cm × 7 cm in area) was found in the right buttock. A sinus had formed and a golden, sand‐like material was being secreted by this sinus.

Several hematologic tests were performed, the results being as follow: C‐reactive protein, 4.33 mg/l; erythrocyte sedimentation rate, 36 mm/ h; mononuclear cell ratio, 9.6%. No bacteria were found on culturing the secretion. An X‐ray film revealed large sheets of high‐density calcification in the pelvis, especially in the the right iliac region (Fig. 2). CT scan also showed large sheets of high‐density calcification in the soft tissue of both buttocks and the anterior part of the lower abdomen, especially in the right iliac region. MRI revealed an abnormal signal in both gluteal regions, T1WI high signal intensity and T2WI low signal intensity surrounded by high signal intensity being found in both. Combined with the history of DM, a diagnosis of DM associated with calcinosis and sinus formation was made.

Figure 2.

Preoperative X‐ray of the pelvis. The X‐ray film reveals large sheets of high‐density calcification in pelvis, especially in the right iliac region.

A fusiform incision was made along the edge of the skin defect and the sinus removed. Flaky calcification was located in the fascial tissue above the muscle tissue, with partial infiltration of the muscle fibers. The scattered calcifications (surrounded by granuloma) between the skin and muscle were completely removed. The incision was closed with full‐thickness sutures and bandaged and the patient was treated with conventional antibiotics post operatively.

The area of flaky calcification resected was 16 cm × 8 cm × 5 cm in size, hard in texture and without a capsule (Fig. 3). Golden, sand‐like calcium deposits infiltrating the fascial tissue were dispersed throughout the specimen. A large number of acute and chronic inflammatory cells had infiltrated the adipose and muscle tissue with abscess formation. Calcification was also observed on pathological examination of a hematoxylin and eosin stained section (Fig. 4). The diagnosis of DM combined with calcinosis was confirmed by histological examination.

Figure 3.

Macroscopic view of the resected specimen, flaky calcification is over 16 cm × 8 cm × 5 cm, the lesion is hard in texture and has no capsule, and golden calcium deposits are dispersed throughout the specimen.

Figure 4.

Postoperative pathology: A large number of acute and chronic inflammatory cells have infiltrated between fat and muscle tissue, and calcification (black arrowheads) can be observed (HE staining ×400).

Discussion

Epidemiology

In the USA, DM has an annual incidence of 2 to 3 cases per million ¹ . Girls are more commonly affected than boys (2.3:1), and the mean age of onset is 10 years ² , ³ . However, the incidence of dermatomyositis in China is not clear. Calcinosis, one of the complications of DM, is a rare disease which was first described by Virchow in 1855. It is characterized by local deposition of insoluble calcium salts and can be caused by local tissue damage (e.g. trauma), extensive tissue damage (e.g. DM), calcium and phosphorus metabolic disorders and so on ⁴ . Calcinosis is related to the severity and duration of activity of disease and is more prevalent in children with chronic DM (about 30% to 70% ⁵ , ⁶ ). However, the incidence of calcinosis caused by DM in China is also not clear.

Diagnosis

Currently, the diagnosis of calcinosis caused by DM is based on comprehensive assessment of typical clinical manifestations, imaging changes and pathological results. Typical clinical manifestations include skin pigmentation, sinuses and hard, inflexible skin. X‐ray examination, CT, MRI and radionuclide bone scan are all useful for detecting the early pathological changes. High‐density clumps which may be round and flaky in shape can be found in the soft tissue on X‐ray films. Biopsy in patients with DM may reveal necrotizing vasculitis and calcium deposits with or without foreign body giant cell reaction in the skin, muscle, and subcutaneous tissue. If the calcium deposits are in the subcutaneous tissue, sand‐like materials (hydroxyapatite crystal) are secreted and the skin may become infected at the sites of calcium deposits. Calcinosis is usually found in the fascial planes of the muscles and tendons. Small, hard plaques or nodules can be palpated just under the skin. These are associated with dark discoloration in the soft tissue, and may restrict severely physical activity. Infiltrates of fibrocytes and giant cells may accompany calcinosis ³ . If any vasculitis (a component of the pathological process) is controlled by aggressive therapy, fewer and smaller lesions and a decrease in calcium deposition should result. Thus aggressive treatment with high‐dose steroids and physical therapy may explain a decreased incidence of calcification ⁶ . However, if treatment is interrupted, deposits of calcium will gradually accumulate, and the surrounding skin will become more indurated. Under these circumstances, friction between the skin and external objects can increase the damage to the skin, resulting in the formation of sinuses.

Clinically, calcinosis needs to be differentiated from progressive myositis ossificans and myositis ossificans as follows: (i) Progressive myositis ossificans is more common in children. It is characterized by progressive calcification in the ligaments, fascia and skeletal muscles of the neck and back, and is often accompanied by finger and/or toe bone dysplasia. (ii) Myositis ossificans occurs most commonly after trauma, is located in trauma sites, and looks like of weak point‐like shadows on X‐ray films. Sinus formation, secretion of a golden, sand‐like substance, and a history of DM are the major features which differentiate calcinosis caused by DM from progressive myositis ossificans and myositis ossificans.

Treatment

No consistently effective medical treatment for calcinosis is available. A small area of calcinosis may be absorbed spontaneously, but large areas of calcinosis need to be resected. In this case, the indications for surgery were clear. Because the calcification was basically located in the subcutaneous fascial planes and not within muscle, the muscle fibers only having point‐like infiltration, the scattered calcifications could be completely removed. In the experience of the present authors, it is not necessary to use an electric knife when cutting widely between the subcutaneous and the calcified plaque. This means that the blood supply to the skin is preserved and the possibility of nonunion of the skin minimized. At the same time, the incision should be sutured as much as possible by primary intention. If there is excessive tension, the incision should be sutured after swelling of the skin has resolved. It is also necessary to reduce tension on the incision with a compression bandage.

This case illustrates that severe calcinosis, although rare, may occur in association with adult DM. Surgical removal of the calcium deposits not only resolved pain and functional impairment, but also resulted in wound healing by primary intention without the occurrence of complications. The patient was satisfied with her final outcome.

Disclosure

The authors did not receive any outside funding or grants in support of their research for, or preparation of, this work.