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E2059. Role of FDG-PET in Sarcoidosis with Atypical Manifestations: Diagnostic Challenges of a Great Masquerader
Authors
  1. Edgar Zamora; Montefiore Medical Center
  2. Kwang Chun; Montefiore Medical Center
  3. Louisiana Rivera Valladares; Montefiore Medical Center
  4. Ana Valdivia; Montefiore Medical Center
Background
Sarcoidosis is a multisystemic disorder, characterized by the formation of noncaseating granulomas, associated with a variety of clinical presentations which can resemble other pathologies. In the absence of a definitive test, its diagnostic workup can become a challenging undertaking based on clinical and radiologic manifestations, exclusion of other diseases, and histopathologic confirmation of noncaseating granulomas. Initiating treatment can be a complicated decision based on multiple factors, including symptomatology, organ involvement, and extent, requiring careful examination for occult disease (1). In patients with advanced sarcoidosis, treatment is usually based on identification of reversible granulomas versus irreversible fibrosis, which can be limited on conventional studies (2). Our purpose is to review different applications of FDG-PET in the evaluation of sarcoidosis with atypical manifestations, based on the experience of a large academic institution.

Educational Goals / Teaching Points
This educational exhibit will review atypical clinical and imaging manifestations of sarcoidosis, demonstrating different applications of FDG-PET for diagnosis and management guidance, including cases with osseous, hepatosplenic, lymphatic, and cardiac involvement.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The diagnosis of sarcoidosis is usually based on pulmonary manifestations. However, this disease may involve nearly any tissue and present without lung manifestations. These atypical presentations often lead to an extensive workup to rule out more common pathologies. While FDG-PET is not routinely indicated, it may have an essential role in some of these cases. While more common, intrathoracic manifestations can still lead to complicated diagnostic questions. Conventional imaging correlates poorly with pulmonary symptomatology and impairment, particularly in advanced disease. FDG-PET can be used in these cases for identification of reversible granulomatous disease and has demonstrated a significant correlation with clinical outcome on follow-up. Extrathoracic manifestations of sarcoidosis are more commonly associated with multisystemic involvement, requiring a thorough assessment for occult disease. While most asymptomatic patients are not treated, involvement of some organs can lead to irreversible fibrosis (e.g. hepatosplenic, cardiac) and require close follow-up with clinical and/or imaging monitoring. Additionally, a history of sarcoidosis can confound the diagnosis of other pathologies (e.g. lymphoma), which can be misdiagnosed as a “flare-up”. This differentiation can be challenging due to the absence of specific serum markers or imaging findings of sarcoidosis. Baseline and follow-up FDG-PET can be used to reevaluate these patients for resolution of abnormal activity following sarcoid-directed treatment.

Conclusion
Sarcoidosis is an inflammatory disease with a highly variable clinical course that can present a number of diagnostic challenges. This educational exhibit reviews the contribution and limitations of metabolic imaging with FDG-PET/CT for the evaluation of sarcoidosis with atypical clinical and imaging manifestations.