Dermatomyositis in a Patient with Cholangiocarcinoma Detected by an [¹⁸F]-Fluorodeoxyglucose Positron Emission Tomography–Computed Tomography Scan

Abstract

Cholangiocarcinoma with paraneoplastic dermatomyositis (DM) is extremely rare, and the whole body positron emission tomography-computed tomography (PET-CT) finding of paraneoplastic DM is rarely reported. We report a 66-year-old woman with metastatic cholangiocarcinoma, initially presented with bilateral proximal muscle uptake on PET-CT without clinical muscle symptoms. The initial interpretation of the high muscle uptake was metastasis to the muscles. However, while awaiting for chemotherapy, muscle weakness evolved and rapidly progressed. The level of creatine phosphokinase was significantly elevated. Electromyography revealed moderate myopathy, and a muscle biopsy showed degenerating myofibers with variable sizes. The diagnosis of paraneoplastic dermatomyositis was made. This case highlights that, although rare, paraneoplastic dermatomyositis can be present with cholangiocarcinoma. Also, muscle inflammation can precede the clinical muscle symptoms, and paraneoplastic DM should be considered as a possible differential diagnosis in the assessment of cancer patients who present with abnormal muscle tracer uptake in PET-CT scans.

F-18-FDG PET/CT findings of paraneoplastic dermatoses

“…Dermatomyositis (DM) is an uncommon idiopathic, inflammatory myopathy characterized by proximal muscle weakness and cutaneous lesions. Skin lesions precede muscle involvement by months or years in more than 50% of DM patients [ 8 , 34 – 42 ]. As cutaneous lesions, a violet-colored or dusky red rash and a heliotrope rash develop, most commonly on face and eyelids and on knuckles, elbows, knees, chest and back.…”

A rare case of cholangiocarcinoma presenting with paraneoplastic syndrome

“…There are only five previously published cases, two of which are not in English. [7][8][9][10][11] No studies have been published regarding cholangiocarcinoma associated with DM sine dermatitis. Identifying the clinical symptoms and being able to recognize paraneoplastic syndrome early can lead to prompt detection and possible treatment of clinical occult malignancies, such as cholangiocarcinoma.…”

“…The association of cholangiocarcinoma with DM is extremely rare. There are only five previously published cases, two of which are not in English 7‐11 . No studies have been published regarding cholangiocarcinoma associated with DM sine dermatitis.…”

Paraneoplastic syndromes in cholangiocarcinoma

“…Dermatomyositis: It is relatively a rare paraneoplastic manifestation of CCA[ 22 ]. It presents as weakness of the proximal group of muscles with a bluish-purple skin lesion on upper eyelids (heliotrope rash) and erythematous papules on knuckles are noticed (Gottron papules) as evident from the study of Suh[ 23 ]. Muscle weakness in dermatomyositis caused by CCA is attributed to increasing energy consumption of carcinoma cells than normal cells, resulting in excessive glucose breakdown[ 24 ].…”