Extensive Intramuscular Manifestation of Sarcoidosis With Initially Missed Diagnosis and Delayed Therapy

A Case Report

Niklaus Meyer; Reto Sutter; Udo Schirp; Andreas Gutzeit

Disclosures

J Med Case Reports. 2017;11(246) 

In This Article

Discussion

Sarcoidosis is a systemic granulomatous disease and the diagnosis is based on a clinico-radiological correlation and histological evidence of non-caseating granulomas. In most cases, lungs are involved primarily and other organs may be affected secondarily. In this case report, we describe an uncommon form of isolated sarcoidosis, involving skeletal muscles of the extremities exclusively without involvement of lungs or other visceral organs or bones.

Lungs and thoracic lymph nodes in patients with sarcoidosis are involved in 95–100% of all cases.[14] In such a combination, the diagnosis of sarcoidosis is relatively simple. In most cases, the diagnosis is confirmed after biopsy of the lymph nodes of the mediastinum or after performing a bronchoalveolar lavage.

In rare cases, sarcoidosis has been shown to involve organs, but sparing the lungs.[15] In such cases, an incorrect interpretation of the findings and delayed treatment can be the result. There have only been two cases previously described, reporting isolated sarcoidosis of the muscle without involvement of the lungs.[12,13] Due to the fact that the lung is generally affected in sarcoidosis, the radiological staging system is still based on chest radiographs even though for the detection of parenchymal involvement high-resolution computer tomography (HRCT) is required. In the case of sarcoidosis outside of the lungs, cross-sectional examinations such as PET/CT and MRI are useful. It is therefore important that radiologists are aware of atypical disease patterns, in order to interpret these accurately and effectively.

In most cases, musculoskeletal involvement of sarcoidosis is associated with lung involvement. Musculoskeletal sarcoidosis mostly involves bones. The typical pattern of such a disease involves lytic lesions of the bones.[15] These lytic lesions are quite typical and specific diagnoses are possible with radiographs. MRI of nodular musculoskeletal sarcoidosis typically revealed a well-demarcated nodule with a heterogeneous signal of the bone.[12,15,16]

In this special situation, we describe a case of sarcoidosis involving the muscles of the extremities and trunk without any involvement of the lungs or bones. Because of this unusual situation, it was more challenging to make an accurate diagnosis and to determine an appropriate treatment.

As described in Figure 1, there was only contrast enhancement with the pattern of myositis. Due to the false assumption of atypical myositis, a PET/CT scan was performed during the course of the disease. The PET/CT scan confirmed extensive myositis without involvement of the bones or other organs. Only the muscle biopsy made the diagnosis evident.

We hope that this case report will help radiologists to better interpret these atypical courses so that the patient can be diagnosed and treated without any delay. Such imaging should suggest a biopsy in similar situations in order to secure a accurate diagnosis.

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