Findings: Multiple hypermetabolic lymphadenopathies involving bilateral hilar, supraclavicular and upper abdominal regions with metabolic activity at the caudate lobe (a). Post treatment image (b) demonstrates interval improvement of liver and abdominal lymph nodes and interval progression of hypermetabolic supra diaphragmatic and left inguinal lymphadenopathy concomitant with progressed FDG avid parenchymal lung involvements.
Differential Diagnosis:
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Pneumoconiosis
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Infectios process such as tuberculosis, EBV.
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Sarcoidosis
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Treated lymphoma with calcified lymph nodes
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Metastases
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Pneumocystis Carinii
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Castleman disease
This case was a 45-year-old male with metastatic alveolar echinococcosis.
Echinococcosis is a parasitic disease that occurs in two main forms in humans:
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Cystic echinococcosis (also known as hydatidosis) caused by Echinococcus granulosus.
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Alveolar echinococcosis cause by Echinococcus multilocularis
Cystic echinococcosis / hydatid disease
Human infection with E. granulosus leads to the development of one or more hydatid cysts located most often in the liver and lungs, and less frequently in the bones, kidneys, spleen, muscles and central nervous system.
The asymptomatic incubation period of the disease can last many years until hydatid cysts grow to an extent that triggers clinical signs, however approximately half of all patients that receive medical treatment for infection do so within a few years of their initial infection with the parasite.
Abdominal pain, nausea and vomiting are commonly seen when hydatids occur in the liver. If the lung is affected, clinical signs include chronic cough, chest pain and shortness of breath. Other signs depend on the location of the hydatid cysts and the pressure exerted on the surrounding tissues. Non-specific signs include anorexia, weight loss and weakness.
Alveolar echinococcosis
Alveolar echinococcosis is characterized by an asymptomatic incubation period of 5–15 years and the slow development of a primary tumour-like lesion which is usually located in the liver. Clinical signs include weight loss, abdominal pain, general malaise and signs of hepatic failure.
Larval metastases may spread either to organs adjacent to the liver (for example, the spleen) or distant locations (such as the lungs, or the brain) following dissemination of the parasite via the blood and lymphatic system. If left untreated, alveolar echinococcosis is progressive and fatal.
Treatment:
- Multidisciplinary: Surgery and Medical treatment with Albendazole for 2 years or more.
Role of FDG PET in metastatic alveolar echinococcosis :
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Assess response to treatment.
Reference:
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Nuclear medicine department of Royal Victoria Hospital, McGill univeresity.
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Salvador, Fernando, et al. "Usefulness of the FDG PET/CT in the management of cystic echinococcosis: A pilot study." Acta Tropica 227 (2022): 106295.
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Husmann, Lars, et al. "Follow-up PET/CT of alveolar echinococcosis: Comparison of metabolic activity and immunodiagnostic testing." Plos one 17.6 (2022): e0270695.
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Caoduro, Cécile, et al. "The role of delayed 18F-FDG PET imaging in the follow-up of patients with alveolar echinococcosis." Journal of nuclear medicine 54.3 (2013): 358-363.