Dermatomyositis (DM) is a rare disorder that typically presents with proximal muscle weakness and a heliotrope rash.1 Although the exact etiology is unknown, DM is an autoimmune disease.2 The cause of this autoimmune reaction is unclear, but in adults there often is a notable correlation between DM and the presence of an underlying malignancy.3,4 Because of its low prevalence and variability in presentation, DM easily can be overlooked or misdiagnosed. In some cases, the cutaneous manifestations of DM may be the first indications of an underlying malignancy, providing an opportunity for early intervention. We report the case of a woman with an ulceronecrotic form of amyopathic DM associated with an unusual internal malignancy.
Case Report
A 59-year-old woman presented to her primary care physician for a pruritic rash on her arms. The patient was given triamcinolone acetonide cream 0.1%, with no improvement. Over the course of several months, the rash progressed to her chest and trunk, predominately in a sun-exposed distribution. The rash was maculopapular and erythematous, with secondary excoriations. No vesicles, tenderness, or discharge were noted. Lupus erythematosus was suspected, and antinuclear antibody test results were normal at a titer of 1:40 in a homogenous pattern. The patient was given a course of low-dose oral prednisone, which did not alleviate her symptoms.
The patient was referred to a dermatologist. By this time, her rash had progressed further and continued to be pruritic. She developed diffuse, edematous, coalescent papules and plaques on the sun-exposed portions of her chest, back, cheeks, upper and lower extremities, and left buttock. Her fingers were edematous and the cuticles were a deep violaceous color. There were numerous nontender papules on her hands, and she experienced pain upon flexion of the digits.
A punch biopsy specimen from the patient's arm demonstrated nonspecific inflammatory findings suggestive of polymorphous light eruption or drug eruption. Results of a repeat antinuclear antibody test were elevated at a titer of 1:640 in a speckled pattern; however, antibodies to SSA, SSB, DNA, ribonucleic protein (extractable nuclear antigen), Scl-70, and Sm antigens were negative.
The dermatologist prescribed a 3-week tapering dose of oral prednisone. At the patient's next visit, the papules that were previously noted on her hands had become purple and brown and a provisional diagnosis of necrotizing vasculitis was made. Cyclophosphamide 75 mg twice daily was added to the patient's treatment regimen. A second biopsy specimen from the patient's right hand was sent for routine histologic examination as well as direct immunofluorescence. The pathologic interpretation again was nonspecific inflammation of the dermis. Direct immunofluorescence revealed no deposition of IgG, IgM, or IgA; C3; or fibrinogen. Additionally, results of an antineutrophil cytoplasmic antibody test, urinalysis, and metabolic panel were within reference range. Posteroanterior and lateral chest x-rays showed a bilateral hilar prominence that appeared to be vascular, a slight prominence of the pulmonary vasculature, and a prominent azygos vein versus adenopathy.
Over the next few days, the lesions on the patient's hands appeared more necrotic. However, she reported that the higher dose of prednisone and cyclophosphamide prevented new lesions from developing.
The internal medicine department was consulted. Although the patient continued to deny muscle weakness, the internist entertained the possibility of amyopathic DM. The rheumatology department also was consulted and the rheumatologist recommended stopping the cyclophosphamide. Ten days after the patient's initial chest x-ray, she underwent a computed tomographic scan of the chest, which showed bilateral pulmonary emboli that appeared to be chronic, pulmonary artery dilation to 4.25 cm, left axillary lymphadenopathy, and retroperitoneal lymphadenopathy. She was instructed to go to the closest emergency department and was admitted for further workup. As part of this workup, her lactate dehydrogenase level was found to be 713 U/L (reference range, 100–200 U/L).
After reviewing the patient's history and noting numerous necrotic lesions on the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints (Figure 1), as well as lesions near the medial canthus (Figure 2), the dermatologist suspected DM secondary to an underlying malignancy. A biopsy specimen from the left third distal interphalangeal joint showed a paucicellular vacuolar interface dermatitis with scattered necrotic keratinocytes typical of DM (Figure 3). In addition, there was dermal vascular thrombosis with a focal paucicellular necrotizing vasculopathy. Direct immunofluorescence results were negative. Test results for an underlying malignancy, including carbohydrate antigen 19-9 (CA19-9), cancer antigen 125 (CA125 ovarian cancer marker), carcinoembryonic antigen, hepatitis panel, and human immunodeficiency virus, were all negative. Test results for a hypercoagulable state, including proteins C and S, lupus anticoagulant, anticardiolipin antibodies, and serum and plasma electrophoresis, also were negative.