Paraneoplastic dermatomyositis and prostate cancer: Myopathy regression under cancer-directed therapy

Abstract

Prostate cancer is the second most frequent malignancy in men worldwide and the fifth leading cause of death. Dermatomyositis (DM) is a rare idiopathic inflammatory myopathy characterized by musculocutaneous manifestations. However, DM can also present as a paraneoplastic syndrome of an underlying neoplasm. We report a case of a 65-year-old man diagnosed with prostate adenocarcinoma in the setting of severe dysphagia, muscle weakness and a facial erythematous rash. At first, the DM-related symptoms resolved with the initial treatment for the underlying malignancy. Yet, they flared up as the tumor progressed. To sum up, DM is a rare systemic disorder with unknown etiology. There is a well-established association between DM and malignancy. Malignancy-headed therapy can improve DM manifestations and the recurrence of DM symptoms may act as an early warning of malignancy relapse.

Keywords: Dermatomyositis; Myositis- Specific Antibody; Paraneoplastic Syndrome; Prostate Cancer; Recurrence.

Figure 1.

Image A: Oblique axial CT plane shows an enlarged and asymmetric prostate (P) with prominent nodular densities extending posteriorly into the periprostatic space. Transrectal prostate biopsy revealed cancer in this area. Image B: Sagittal CT plane. Image C: different oblique axial CT plane. These latter planes demonstrate the tumor (T) also spreading superiorly, with infiltration of fat between the left seminal vesicle (SV) and the rectum wall (R) and loss of the fat planes between these structures. CT is not accurate to characterize locally the prostatic cancer. MRI is the imaging method for regional staging, but the presence of disseminated disease, shown by non-regional/distant metastatic adenopathies (Adp), made MRI unnecessary.

Figure 2.

CT images. The right image (Axial CT scan) shows progressive disease with an increase of retroperitoneal lymph nodes, comparing to the CT performed nine months before (left image).