This patient was diagnosed with dermatomyositis, fitting 4 out of the five diagnostic criteria, as outlined above: proximal muscle weakness, CPK and LDH elevations, consistent with myositis EMG, and skin manifestations [4, 5]. The latter were as follows: purple confluent discoloration and swelling of the eyelids - heliotrope rush, the V-shape rash with areas of hyperpigmentation of his upper torso and shoulders, back, knees, and erythematous papules over joints - 'Gottron's sign', and hypertrophic changes of palms and fingers - 'Mechanic's hands'. The diagnosis is confirmed if a patient presents with at least 4 diagnostic criteria for PM or 3 for DM [4, 5]. The fifth criterion which is confirmation of inflammatory infiltrations on muscle biopsy was not done in this case. Since our patient exhibited clinical and laboratory findings consistent with inflammatory myopathy with skin manifestations present, our diagnosis was consistent with dermatomyositis.
The cause of the disease remains unknown. Altered immune response towards viral infection is considered to play a major role [1, 2]. Vascular deposits of immune complexes and complement, leading to endothelial cell injury and small vessel obstruction are most important pathogenetic factors underlying the disease [6]. The muscles and endothelial cells are infiltrated with predominance of T CD4+ cells in DM and T CD8+ cells in PM patients [6]. An association of tumor necrosis factor alpha and HLA polymorphisms with adult dermatomyositis has recently been reported [7, 8]. Our patient exhibited all reported skin manifestations of DM which were: a heliotrope rash, which is a purple discoloration and swelling of the eyelids, Gottron's sign demonstrated with erythematous papules over joints, and mechanic's hands, which are: erythematous and hypertrophic skin changes of palms and fingers [1–5]. Hemoptysis, progressive dyspnea, subtle dry cracles and wheezing on auscultation, with bilateral patchy consolidations and ground-glass opacities on chest X-ray and CT scans confirmed lung interstitium disease association in our case. Hemoptysis and pulmonary embolism, lack of significant muscle weakness at the onset of the disease masqueraded underlying DM and delayed proper diagnosis. Lung involvement has been reported in minority of PM and DM cases, influencing the course and worsening prognosis in most of the cases [9, 10]. An association with other connective tissue disorders (overlap syndrome) and malignancy has also been reported [9–13]. The course of the disease is usually steadily progressive, leading to profound symmetrical skeletal muscle weakness of all extremities. Patient management includes careful evaluation for underlying malignancy, physical therapy, antihistamines, sunscreen, and oral corticosteroids [14]. Alternative therapies include corticosteroid-sparing agents, cytotoxic drugs, and more recently monoclonal antibodies with cutaneous lesions treatment [14–18]. Irresponsive disease, delay in diagnosis and the underlying malignancies worsen disease prognosis.