Not all that shines is cancer: pulmonary cryptococcosis mimicking lymphoma in [(18)] F fluoro-2-deoxy-D-glucose positron emission tomography

Abstract

We report of a case of pulmonary cryptococcosis mimicking lymphoma in a positron emission tomography (FDG-PET) scan. A 62-year old man with diffuse large B-cell lymphoma had complete resolution of abdominal and pulmonary lesions after three cycles of rituximab-based chemotherapy (R-CHOP). However, FDG-PET showed new pulmonary nodules, suggesting active lymphoma. Chronic inflammatory granuloma was seen in the histopathological exam, with round-shaped structures compatible with fungus, later identified as Cryptococcus neoformans on culture. The lesions disappeared after 6 weeks of fluconazole therapy, and the patient could continue chemotherapy without further infectious complications.

An Avid Imitator

“…We know little about the risk for cryptococcosis in presumably lower net states of immunosuppression, for example with low-intensity chemotherapy, or early in the course of lymphoma treatment. In the two studies mentioned above, 100% [ 2 ] and 61% [ 3 ] of affected patients had significant lymphopenia, an important risk factor for cryptococcal disease, as exemplified in the present and previous case reports [ 5-7 ].…”

“…Cryptococcosis typically affects patients who have impaired cell-mediated immunity or receive high-dose steroids [ 3 , 5-8 ]. In two case series of cancer patients with proven cryptococcal infection, 83% [ 2 ] and 65% [ 3 ] had lymphoproliferative disorders, most of whom had advanced cancer and were heavily treated.…”

“…The clinical and radiological presentation of cryptococcosis in cancer patients is non-specific and frequently mimics progression of primary malignancy or metastatic disease [ 3 , 5 , 7 , 9 ]. In one study of cancer patients with cryptococcal disease, pulmonary cryptococcosis was initially misdiagnosed as cancer in 35%, healthcare-associated pneumonia in 22%, and indeterminate lung nodules in 19% [ 3 ].…”

“…In one study of cancer patients with cryptococcal disease, pulmonary cryptococcosis was initially misdiagnosed as cancer in 35%, healthcare-associated pneumonia in 22%, and indeterminate lung nodules in 19% [ 3 ]. 18-FDG PET/CT is often used to differentiate between benign and malignant lesions, and an SUV of approximately 5 is typically considered a reliable cutoff [ 5 ]. Nevertheless, in our patient, cryptococcal involvement of lymph nodes manifested with an SUV of 7, and in another similar case with an SUV of 13 [ 5 ].…”

“…18-FDG PET/CT is often used to differentiate between benign and malignant lesions, and an SUV of approximately 5 is typically considered a reliable cutoff [ 5 ]. Nevertheless, in our patient, cryptococcal involvement of lymph nodes manifested with an SUV of 7, and in another similar case with an SUV of 13 [ 5 ]. In a series of seven patients with pulmonary cryptococcal lesions, SUV values ranged between 2.2 and 11.6 [ 9 ].…”