524 - A Case Report of Metastatic Prostate Cancer Mimicking as Parsonage-Turner Syndrome

Thursday, February 22, 2024

5:00 PM – 6:30 PM EDT

Presenting Author(s)

Won J. Jeong, MD

Resident Physician
Baylor College of Medicine
Houston, Texas, United States
LL

Loc Lam, DO

Resident Physician
Baylor College of Medicine
Houston, Texas, United States

Co-Author(s)

JE

Julia Evans, BS

Medical Student
University of Toledo College of Medicine
Lima, Ohio, United States

Corresponding Author(s)

SI

Stacey Isidro, MD

Resident Physician
Baylor College of Medicine
Houston, Texas, United States

Co-Author(s)

PP

Paul Paily, MD

Associate Professor
Baylor College of Medicine
Houston, Texas, United States

Case Diagnosis: Right shoulder pain secondary to metastatic prostate cancer

Case Description: A 64-year-old male with a history of chronic low back pain, benign prostatic hyperplasia, urinary retention, and chronic kidney disease presented with acute intense right shoulder pain without an inciting event. The pain radiated from the right scapular region to the right neck, anterior chest, arm, forearm, and hand in nonspecific dermatomes. Examination revealed paresthesia of digits 1, 3, and 5, and atrophy of the supraspinatus, infraspinatus, and the clavicular head of the pectoralis major. The range of motion and the strength exam of the shoulder were limited due to pain. Cervical spine MRI was inconclusive, and symptoms improved slightly with methylprednisolone. Parsonage-Turner Syndrome was suspected. Humeral X-ray revealed osteolytic and osteoblastic lesions in the right proximal humerus. CT scan of the shoulder revealed metastatic lesions in the right humerus. Subsequently, a humeral lesion biopsy confirmed the diagnosis of metastatic prostate cancer.

Discussions: Parsonage-Turner Syndrome, or idiopathic brachial neuritis, is a rare cause of brachial plexopathy characterized by an abrupt severe shoulder pain followed by weakness and paresthesias in the upper limbs. It is diagnosed based on history, symptoms, and careful neuromuscular exam. However, as the name suggests, it is a diagnosis of exclusion. Additional diagnostic studies like EMG and imaging must be obtained to exclude other causes of brachial plexopathy. As demonstrated in this case, a rare metastasis of prostate cancer to the proximal humerus can mimic the clinical symptoms of Parsonage-Turner Syndrome. Therefore, imaging studies such as MRI or CT scan may be crucial in diagnosing and further guiding the treatment of brachial plexopathy.

Conclusions: This case illustrates the importance of obtaining diagnostic imaging studies in patients with suspected Parsonage-Turner Syndrome and considering metastatic lesions as part of the differential.