We are reporting a case of a 61-year-old female patient who presented with weight loss and fatigue for 6 months. She had palpable cervical nodes.
She underwent PET-CT on 26-01-2016 which documented metabolically active extensive pulmonary pleural nodularity with an avid mass in the left upper lobe. There were supraclavicular, mediastinal, paraoesophageal and upper abdominal lymph nodes as well.
Based upon these findings she underwent CT guided biopsy of left apical lung mass.
Sarcoidosis is a multisystem inflammatory disease which is characterized by chronic non-granulomatous inflammation. The most common sites of involvement are lungs and mediastinal lymph nodes. The most common sites of lymphadenopathy are mediastinal lymph nodes with symmetrical involvement of the right paratracheal and bilateral hilar nodes. It may involve lymph nodes at atypical sites which could be mistaken for other potential causes of lymph node enlargement like lymphoma and tuberculosis. Pulmonary involvement is seen as nodules with perilymphatic distribution. Ill-defined pulmonary opacities are less common [1, 2]. Atypical pulmonary involvement may mimic primary lung cancer. Gold standard for diagnosis is histopathology.
Our case had both typical and atypical imaging features [Fig. 1, 2, 3]. Later it was histopathologically proven as sarcoidosis. There was non-caseating granulomatous inflammation without necrosis. Ziehl-Neelsen and GMS stains and cultures for mycobacteria were negative. She was given steroid treatment. Post biopsy scans documented complete metabolic response with partial morphologic response [Fig. 4, 5, 6].
FDG-PET CT has an emerging role in the evaluation of sarcoidosis as there is increased FDG uptake by inflammatory cells. Simultaneous acquisition of morphological and functional data can identify occult disease sites which are not detected by other imaging techniques. Similarly, FDG PET-CT aids in monitoring treatment response. This is especially useful when the disease remains morphologically stable. In these cases response can still be assessed based on FDG uptake. FDG PET-CT is especially useful to assess active and fibrotic components of the disease .
In conclusion, sarcoidosis should always be kept in the differential list in patients having mediastinal lymph adenopathy with pulmonary involvement even with atypical sites of nodal involvement.
Differential Diagnosis List
Lung cancer with metastatic lymph adenopathy