IS Case 266: Granulomatous disease mimicking lymphoma

Sara Ann Majewski, MD


Imaging Sciences URMC 2009
Publication Date: 2009-07-29

History

Patient is a 46-year-old male who finished treatment for diffuse large B-cell lymphoma four months prior to the current CT. CT revealed hypermetabolic adenopathy in the abdomen and chest region, which was treated with a single cycle chemotherapy. A PET/CT was requested to evaluate for suspected disease recurrence.

Findings

There is increased fluorodeoxyglucose (FDG) uptake in the spleen and in multiple normal and borderline enlarged lymph nodes.

Diagnosis

Granulomatous disease mimicking lymphoma

Discussion

Fluorodeoxyglucose positron emission tomography (FDG-PET) is used in the evaluation of known or suspected malignancy. Tracer uptake is nonspecific and occurs according to tissue metabolism.

Inflammatory changes and active granulomatous infections can result in increased 18F-FDG uptake, causing interpretation difficulties. Some examples of these conditions are tuberculosis, sarcoidosis, glandular fever, Epstein-Barr virus and fungal infections such as histoplasmosis and coccidiomycosis.

In some cases, FDG uptake in lymph nodes and organs can mimic malignancies like lymphoma and diffuse metastatic disease. FDG uptake in granulomatous disease is typically nonspecific in intensity and pattern and is usually not useful for initial definitive diagnosis. Pathologic correlation is often needed in cases of active granulomatous diseases to exclude malignancies such as lymphoma.

In the case of the patient described above, the PET/CT findings were concerning for active lymphoma. Right supraclavicular lymph node biopsy was suggested if pathologic diagnosis was needed. The patient underwent right supraclavicular lymph node biopsy shortly after the PET/CT scan which revealed multiple fragments of lymphoid tissue that have been largely replaced by epithelioid, noncaseating granulomata. Stains ruled out infectious causes of granulomatous inflammation. These findings may represent sarcoidosis or the sequelae of prior treatment.

References

  1. Hoppe RT, Mauch PM, Armitage JO, Diehl V, Weiss LM, Eds. Hodgkin Lymphoma. 2nd ed., Philadelphia: Lippincott Williams & Wilkins, 2007.
  2. Mettler FA Jr, Guiberteau MJ. Essentials of Nuclear Medicine Imaging. 5th ed., Philadelphia: Saunders Elsevier, 2006.
  3. Prabhakar HB, Rabinowitz CB, Gibbons FK, et. al. Imaging features of sarcoidosis on MDCT, FDG PET, and PET/CT. AJR Am J Roentgenol. 2008 Mar;190(3 Suppl):S1-6. PMID: 18287458 [PubMed]

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