A valid association between DM and cancer is supported by the fact that when a malignancy is found, it tends to be one of a subset of cancers. Lymphoma, ovarian, lung, and pancreatic malignancies dominate this subset.3,4,14,28 While ovarian cancer is only the sixth most common malignancy among females in the United States,33 studies have determined the SIR for ovarian cancer in a group of patients with DM was between 10.5 (95% CI, 6.1-18.1) and 15.5 (95% CI, 4.2-39.8) compared with case controls.4,28 During the first year of disease, the SIR for ovarian cancer in this same group was 38.2 (95% CI, 10.8-102.4).28 In most cases of ovarian cancer, the clinical features of DM were recognized before the cancer.34 If DM can be recognized early, it may allow for timely intervention and cure of a potentially lethal disease.
Conclusion
This case report describes a patient with CADM and an internal malignancy, a known association.8,13,35,36 However, at least 2 studies have shown a lack of malignancies in CADM, particularly in white patients.37,38 To our knowledge, this case report of CADM is the first association with a poorly differentiated, nonpulmonary, small cell carcinoma, and only the second report of a patient with CADM secondary to a malignancy with necrotic DM lesions of the skin.39 In addition, the histologic association of prominent vasculopathic changes with vacuolar interface dermatitis is unusual, and in our case, it resulted in a delay in histologic diagnosis.
There is no established clinical presentation of DM or CADM that is pathognomonic for the presence of an underlying malignancy. There must be a high degree of suspicion of cancer in any patient presenting with the signs or symptoms of either DM or CADM. On diagnosis of DM or CADM, a workup to include breast, colon, and pelvic examinations; complete blood cell count; liver function enzyme and stool guaiac tests; urinalysis; and chest x-rays are indicated. For females, a CA125 test to screen for ovarian cancer also is indicated.13