Introduction
Sarcoidosis is a systemic granulomatous disease with involvement of various organs [
1]. The various types of cutaneous sarcoidosis have been described previously, but the relation between cutaneous sarcoidosis and severity of general sarcoidosis has been shrouded in mystery [
2].
Myocardial sarcoidosis is known as a significant complication, but Holter electrocardiographic monitoring and echocardiograms might not be sensitive enough to detect cardiac involvement [
3]. Although gallium (
67Ga) scintigraphy has been recommended as a diagnostic tool,
18F-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) imaging might be more sensitive in detecting sarcoidosis [
4]. Previous reports have suggested no significant difference between Ga scintigraphy and PET-CT [
5]. Because myocardial sarcoidosis may result in unexpected sudden death [
6], cardiac abnormalities should be adequately evaluated early in the course of the disease.
In this report, we investigated the relationship of cutaneous sarcoidosis and internal involvement, including myocardial sarcoidosis, using PET-CT and Ga scintigraphy. Among 12 patients, we found that 10 patients (83%) had internal involvement (Table
1). To the best of our knowledge, this report is the first to document that PET-CT is useful for detecting internal involvement in the cutaneous multiple plaque type of sarcoidosis.
Table 1
Patient demographics, affected areas, clinical types of sarcoidosis and complications
1 | M | 66 | Plaque (face) | PET | + | Mediastinal LN diaphragm left parotid gland | Sjögren syndrome |
2 | F | 74 | Plaque (face) | PET | + | Mediastinal LN | Hepatitis C virus |
3 | F | 93 | Plaque (face) | PET | – | Left supraclavicular LN Mediastinal LN retroperitoneal LN | Lung tumor |
4 | F | 48 | Plaque (face) | PET | + | Mediastinal LN retroperitoneal LN Periaortal LN neck LN | Past history of lung tuberculosis Hepatitis B virus |
5 | F | 63 | Nodule (face) | Ga Scintigraphy | – | Muscle sarcoid (gastrocnemius) | Rheumatoid arthritis |
Sjögren syndrome |
6 | F | 59 | Nodule (face) | PET | – | Mediastinal LN | – |
7 | F | 68 | Nodule (face) | PET | – | Mediastinal LN right leg skin | Antinuclear antigen–positive (×1280) |
8 | F | 58 | Nodule (face) | Ga Scintigraphy | – | Mediastinal LN | Hashimoto's disease |
9 | F | 32 | Nodule (face, right knee) | PET | – | – | – |
10 | F | 55 | Scar (both knees) | PET | + | Mediastinal LN Left supraclavicular LN Retroperitoneal LN | – |
11 | F | 43 | Scar (both knees) | PET | – | Mediastinal LN | Myoma uteri |
12 | M | 73 | Subcutaneous type (face) nodule (left arm), papules (entire body) | Ga Scintigraphy | – | – | Past history of lung tuberculosis Hepatitis C virus |
Discussion
Sarcoidosis is a multisystem granulomatous disease of unknown etiology [
1]. We performed screening for internal involvement by PET-CT and Ga scintigraphy in 12 cutaneous sarcoidosis patients. The results showed the usefulness of PET-CT for detection of internal involvement, especially for myocardial sarcoidosis. Our patients who had myocardial sarcoidosis did not show any subjective symptoms or any remarkable changes at the time the first electrocardiogram was taken. Because myocardial sarcoidosis may cause unexpected sudden death [
6], cardiac abnormalities should be evaluated appropriately early in the course of the disease [
4]. Although cardiac magnetic resonance imaging with gadolinium enhancement may be another approach, it detects only heart lesions [
1‐
4]. PET-CT scans can allow clinicians to detect sarcoid lesions of the whole body and are useful for the follow-up of patients who receive pacemakers [
1‐
4].
The various types of cutaneous sarcoidosis have been described previously, but the relation between cutaneous sarcoidosis and the severity of general sarcoidosis has been shrouded in mystery [
2]. Our patient examinations revealed that myocardial sarcoidosis was more prevalent in patients with the multiple facial plaque type of cutaneous sarcoidosis (Table
1). On the one hand, the severity of myocardial sarcoidosis did not correlate with cutaneous sarcoidosis involvement (compare Figure
1A with Figure
2A). On the other hand, four patients had various multiple internal and LN involvements that were detected by PET-CT (Table
1), and three of these four patients also had myocardial sarcoidosis (75%). This pattern suggests that multiple lesions detected by PET-CT might be associated with myocardial sarcoidosis.
Sarcoidosis is accompanied by many complications, which include various autoimmune diseases that may cause lymphadenopathy [
7,
8]. Our patients had Sjögren syndrome, rheumatoid arthritis, Hashimoto disease and positive ANAs (×1280). This may be related to the immunopathogenic mechanism of sarcoidosis, which includes T-helper type 1 cell–related, uncontrolled, cell-mediated immunity.
A recent report showed the relation of sarcoidosis to hepatitis C viral infection [
9]. One is triggered by antiviral therapies (75%), but the other is unrelated to the treatment (25%) [
9]. The myocardial sarcoidosis was also associated with viral hepatitis in three cases (67%) without treatment by interferon. The significance of the relation of myocardial sarcoidosis and viral hepatitis remains to be determined.
Mycobacterium and
Propionibacterium have been identified as causative antigens of sarcoidosis [
10]. The higher ratio of history of tuberculosis (17% vs. 9.2% of the same-age controls in 2009) might suggest the relationship between tuberculosis and sarcoidosis. In another report, Tchernev
et al. suggested that the autoimmune etiology of sarcoidosis might occur through a process of molecular mimicry of infectious or other environmental antigens to host antigens [
2].
Conclusion
PET-CT can be used to detect sarcoid lesions of the whole body and is useful in patient follow-up. PET-CT has been shown to be quite useful for the detection of myocardial sarcoidosis, which was highly associated with the multiple facial plaque type of sarcoidosis. Although other associated involvements were noted in our patients, the significance in terms of the development of clinical sarcoidosis remains to be determined.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
SN conceived of the study, participated in its design and coordination and drafted the manuscript. KN and KT participated in the design of the study and performed the statistical analysis. TM and YH conceived of the study. TD and HI drafted the manuscript and decided the results after discussion with SN. All authors read and approved the final manuscript.