A 29-year-old man with a painless mass on his back.
History of the present illness
The patient had noticed a painless mass over his right midback 2 years earlier. The mass had increased gradually in size. He had no history of fever, weight loss, anorexia, back pain, or similar lesions at any other site on his body. The overlying skin did not appear to be involved, and there was no history of any injury, injection, or surgical procedure on that site. There was no sensory loss or burning or tingling over or around the mass lesion, nor a history of chest pain, cough, hemoptysis, or breathlessness.
Examination revealed a well-demarcated mass of moderate firmness that was approximately 7 × 5 cm2 in dimension. There was no erythema or tenderness to suggest inflammation. There was no spinal tenderness or gibbus, and scapular movements were not restricted. The remainder of the physical examination was unremarkable. Spine radiographs did not reveal any vertebral damage to suggest Pott's spine.
Ultrasonography revealed a localized intramuscular abscess on the right scapular area. The patient was subsequently lost to followup for 1 year, during which time he underwent multiple incision and drainage procedures of the presumed abscess at other clinics. However, the lesion did not resolve. Cultures of the pus-like material exuded during abscess drainage were negative on several occasions.
When the patient returned to our clinic, the mass had grown significantly in size and now occupied nearly two-thirds of the right side of his back and the side of his trunk (Figures 1A and B). The mass was firm, nontender, and nearly oblong, with few fluctuant areas. It was difficult to determine if the tumor was fixed to underlying structures, but the overlying skin was not tethered. Shoulder girdle movement and chest expansion were nearly normal. There were no enlarged regional lymph nodes. There was no fever and a complete review of systems was otherwise noncontributory.
The patient had been diagnosed with dermatomyositis 7 years before presentation with the mass. His dermatomyositis had been characterized by polyarthritis, gradually progressive proximal muscle weakness, and ulcers over both elbows. There was no history of photosensitivity, malar rash, cough, dyspnea, dysphagia, or dysphonia. Examination had revealed a classic Gottron's sign over the dorsal surfaces of his metacarpal, proximal interphalangeal, and distal interphalangeal joints; punched out ulcers over both elbows; and proximal muscle weakness.
The patient's muscle enzymes (creatine kinase, lactate dehydrogenase, and aspartate aminotransferase) were elevated more than 4-fold at presentation, accompanied by elevations in the erythrocyte sedimentation rate and C-reactive protein concentration. An enzyme immunoassay for antibodies to the human immunodeficiency virus was negative, as were assays for antinuclear antibodies and anti-Mi2 antibodies. Electrodiagnostic studies and the result of a muscle biopsy confirmed the diagnosis of dermatomyositis.
The patient's elbow ulcers healed following the institution of daily oral prednisolone (1 mg/kg). His muscle power improved, and the muscle enzymes normalized. He was subsequently treated with weekly oral methotrexate followed by a gradual prednisolone taper. However, the patient developed recurrent episodes of fingertip infarctions, ulcers over the gluteal region, and recurrent muscle enzyme elevation despite methotrexate 25 mg/week. His condition required long-term oral prednisolone use at dosages of more than 15 mg/day. The addition of azathioprine to his regimen of methotrexate and prednisolone led to a sustained response and the ability to taper his prednisolone to 5 mg/day. Over the next 2 years, the patient experienced 3 episodes of vasculitic ulcers, an episode of a photosensitive malar rash, and 3 myositis relapses. Each of these episodes improved with transient increases in his daily prednisolone dose. After that period, the patient entered a 2-year remission, with no clinical or serologic signs of either active muscle or active skin disease.
Family and social history
The family history was negative for rheumatic illnesses and other disorders that bore any similarity to the way in which he had presented. The patient was single and did not drink alcohol or smoke cigarettes.
Medications and allergies
The patient remained on azathioprine 125 mg/day, methotrexate 25 mg/week, folic acid 1 mg/day, and prednisone 5 mg/day. He had no known drug allergies. The results of the patient's routine laboratory examination are shown in Table 1.
CK = creatine kinase; LDH = lactic dehydrogenase; AST = aspartate transaminase; ALT = alanine transaminase; WBCs = white blood cells; ESR = erythrocyte sedimentation rate; CRP = C-reactive protein.
Presentation with back mass
After 1 year, lost to followup (presenting with huge back mass)
Inorganic phosphorus, mg/dl
At first presentation (diagnosed as dermatomyositis)
Total WBCs, cells/μl/mm3
ESR (Westergren), mm/hour
CRP level, mg/liter
A diagnostic test was performed.
A young man with a history of dermatomyositis presented with a chronic, slowly enlarging tumoral mass on the back. His dermatomyositis appeared to be well controlled.
A dermatomyositis-associated cancer was one possible explanation for the patient's tumor. Dermatomyositis can present as part of a paraneoplastic syndrome, and the discovery of an underlying malignancy frequently occurs after the diagnosis of dermatomyositis. We therefore entertained that the soft tissue mass was a dermatomyositis-related malignancy, e.g., a sarcoma. To our knowledge, however, no association between sarcomas and paraneoplastic syndromes leading to dermatomyositis has been reported. The most commonly reported malignancies in dermatomyositis are lymphomas and ovarian, gastric, and lung cancers (1–3). Among soft tissue tumors, only Kaposi's sarcoma has been reported in association with dermatomyositis. However, this tumor is believed to arise as a complication of immunosuppressive therapy for dermatomyositis rather than as the inciting malignancy (4, 5).
A complication of dermatomyositis itself was another possible explanation for the growth. Both cutaneous and subcutaneous manifestations of dermatomyositis are well described. Whereas patients with active disease can have vasculitic manifestations on the skin that can lead to ulcers, a photosensitive rash, or Gottron's rash, those with longstanding disease can present with cutaneous scars or calcinosis. The manifestations are mainly nodules or plaques of calcium salts. These tend to occur over pressure points such as the back of the elbow, occiput, and gluteal region. These deposits sometimes occur within the subcutaneous tissue or even in an intramuscular plane. Although calcinosis may become widespread, tumors such as that in our patient have not been described.
Soft tissue sarcomas can arise from the thoracic wall. Myogenic sarcomas can be relatively asymptomatic and grow slowly to large sizes (6). Such lesions are possible explanations for our patient's problem, but to our knowledge, soft tissue sarcomas developing in the chronically inflamed muscle tissue of dermatomyositis have never been described.
Complications of the treatment of dermatomyositis were also considered in this case. Patients receiving immunosuppressive medications are prone to the development of infective complications, such as a “cold abscess” associated with a Mycobacterium tuberculosis infection. There was no gibbus or localized tenderness over the spine, and the patient denied fever, anorexia, weight loss, cough, or lymphadenopathy. Radiology of the spine did not show any lesion suggesting Pott's spine, and pus-like aspirate was negative for acid-fast bacilli on several occasions.
Finally, the possibility of a process completely unrelated to dermatomyositis needed to be excluded. Soft tissue masses such as liposarcomas, hemangiosarcomas, and neurofibrosarcomas have all been reported to arise from the trunk. Chronic expanding hematomas (7) have been reported to arise even without a history of trauma.
Radiographs of the mass showed calcified specks over the intramuscular plane of the right scapula (Figure 2A), and a computed tomography (CT) scan revealed a multiloculated calcified cyst (Figures 2B and C). There were no other areas of calcification in the skin, subcutaneous tissues, or intermuscular plane. There was no evidence of malignancy; no bone, pleura, or lung involvement; and no necrotic, scarred, abnormal adjoining muscles on the CT scan.
The diagnostic procedure consisted of a surgical procedure to remove the mass. During the operation, multiple large chalky deposits were found. The largest measured 17 × 9 cm2. This entire mass was removed from the intramuscular plane (Figures 1C and D). Histologic examination of this mass showed dystrophic calcification within an epidermal cyst. The adjoining muscle histology was normal, and there was no evidence of malignancy. The entire cyst wall had been replaced with calcified tissue as well as with bone formation (Figure 3). Only a few areas showed an epithelial lining, which confirmed the origin of the dystrophic calcification as an epidermal cyst (Figures 3B and C).
Giant dystrophic calcification of an epidermal cyst in adult dermatomyositis.
We describe here a patient with longstanding dermatomyositis who presented with massive calcification of an epidermal cyst. The patient's dermatomyositis was in remission on his regimen of methotrexate, azathioprine, and low-dose prednisolone, and remained so during followup after removal of the mass. The cystic calcified tissue did not recur after removal. Although dystrophic calcification is a known complication of dermatomyositis, our literature search did not reveal any previous report of such a huge cystic deposit.
Soft tissue calcifications in dermatomyositis are particularly common in juvenile disease, where this complication occurs in as many as 60% of cases (8). Calcification in both the juvenile and adult forms of dermatomyositis is thought to stem from poorly controlled disease and undertreatment. Tissue calcification in dermatomyositis usually presents as diffusely scattered sheets of idiopathic calcinosis or as dystrophic calcification in the diseased skin or muscle. Different presentations, including superficial plaques or nodules in the skin or subcutaneous tissue (calcinosis cutis), deep linear deposits along fascial planes of the muscles, and an extensive superficial, lacy reticular calcium deposit diffusely covering a large part of the body (calcinosis universalis), have been described in patients with juvenile dermatomyositis (8–10); however, large cystic presentation as in our case has not been reported.
Calcification is usually a late complication of dermatomyositis and often becomes a stubborn, chronic problem. Spontaneous regressions of the calcium deposits are rare, and the deposits respond poorly to various medical modalities of management, including calcium-channel blockers, anticoagulants, or colchicine (11). Sometimes, as in our patient, the deposits are amenable to surgical removal. Dystrophic calcification is known to involve epidermal cysts. Histopathologic evaluation of the biopsy of our patient revealed areas of squamous epithelial lining of the cyst, confirming this to be an epidermal cyst (Figures 3B and C). Most of the wall had been replaced by calcification. There were multiple areas of ossifications, especially in the cyst lumen. Because the patient had harbored the lesion for more than a year, it was likely that the entire epithelial lining had also been involved by the process of calcification. Multiple areas of ossification supported the longstanding nature of the pathologic process. Although a giant calcified pseudocyst has been reported in a patient with overlap syndrome (12), to the best of our knowledge, such a massive dystrophic calcification in a true epidermal cyst has not been described in dermatomyositis or other connective tissue disorders.
Dystrophic calcification represents a local pathologic defect favoring calcium salt deposition. In dermatomyositis, dystrophic calcification is a well-recognized complication of inflammation within the skin or muscle, even though the precise precipitants of this condition are not clear. There is a strong consensus that dystrophic calcification is most likely to occur in patients whose dermatomyositis has been aggressive and persistent (13, 14). Undertreatment is also considered to play a role in some cases. Calcification is usually associated with “burnt-out” muscle disease, although there have been reports that calcinosis may be associated with relapse of dermatomyositis (15). The calcified deposit in dermatomyositis contains hydroxyapatite crystal as well as bone proteins (13). It is possible that a nidus of degenerated material in the skin or muscle initiates the pathologic calcification (16).
The patient was doing well on hydroxychloroquine and 2.5 mg of prednisolone subsequent to cyst excision. Ten months after excision of the calcified cyst, he presented with multiple subcutaneous nodules over the legs, elbows, and dorsum of the hands, diagnosed radiologically as soft tissue calcifications, with those over the right elbow and left knuckles exuding small chalky material. He was diagnosed as having classic calcinosis cutis developing a few years after development of atypical dystrophic calcification of the epidermal cyst, and was initiated on calcium-channel blockers. His muscle power as well as muscle enzymes, however, continue to be normal; there was neither recurrence of an active dermatomyositis rash nor recurrence of calcification over the surgery site on the back.
All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Dr. Shrivastava had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study conception and design. Shrivastava, Khanna, Metgud, Malur.
Acquisition of data. Shrivastava, Khanna, Metgud, Malur.
Analysis and interpretation of data. Shrivastava, Khanna.