Pulmonary intravascular lymphoma detected by FDG-PET.

A 69-year-old woman visited our hospital with a 2-month history of general fatigue, high fever, and dyspnea. Physical examination showed no abnormalities in superficial lymph nodes or respiratory sound. A chest computed tomography scan showed diffuse mild ground-glass attenuation in bilateral lung fields, whereas FDG-PET revealed intense uptake of FDG throughout the lung.

A 69‐year‐old woman visited our hospital with a 2‐month history of general fatigue, high fever, and dyspnea. She also complained of night sweats without body weight loss. Physical examination showed no abnormalities in superficial lymph nodes or respiratory sound. However, severe oxygen desaturation became evident even after ten‐meter walking. Advanced lung cancer, severe emphysema, and military tuberculosis were excluded because of normal chest radiograph.

We considered adult‐onset Still's disease, pulmonary embolism, and hematologic malignancy as further differential diagnosis of the patient's symptom. A blood test showed a neutrophil‐dominant normal white blood cell count of 8040/μL (0.5% atypical lymphocytes), mildly elevated ferritin of 378.5 ng/mL and undetectable fibrin and fibrinogen degradation products, whereas serum lactate dehydrogenase (LD) was greatly increased to 1475 U/L. Adult‐onset Still's disease was unlikely because of no findings of specific skin lesions or severe elevation of ferritin. Pulmonary embolism was ruled out by a contrast‐enhanced computed tomography (CT) scan. The patient's symptoms and very high levels of LD indicated the possibility of malignant lymphoma.

Subsequent examination revealed an increased serum level of soluble interleukin‐2 receptor (2771 IU/mL) being compatible with lymphoma. Whole‐body CT showed no lymphadenopathy, but diffuse mild ground‐glass attenuation was noted throughout the lung, where 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) revealed intense FDG accumulation with SUVmax of 6.81 (Figure 1). A transbronchial lung biopsy was performed, and many abnormal lymphocytes were seen inside the lumen of pulmonary capillaries. The lymphoid cells were negative for CD3, weakly positive for CD5, and positive for CD20 with high expression of Ki‐67 (Figure   2). These findings led to a diagnosis of intravascular large B‐cell lymphoma.

Figure 1

A chest computed tomography scan did not show a nodular lesion or a consolidation area but showed diffuse mild ground‐glass attenuation in bilateral lung fields (A). Intense uptake of 18F‐fluorodeoxyglucose was observed throughout the lung by positron emission tomography (B)

Figure 2

Representative hematoxylin–eosin staining of lung tissue from the patient (A). There were many abnormal lymphocytes localized in the lumen of pulmonary capillaries (arrowheads). Immunohistochemical staining demonstrated that abnormal lymphocytes were negative for CD3 (B), weakly positive for CD5 (C), and positive for CD20 (D) with high expression of Ki‐67 (E), indicating B‐cell lineage lymphoma

Intravascular lymphoma (IVL) is an aggressive disease for which histopathological diagnosis from involved organs and early treatment is required.1 It is often difficult to decide the biopsy site by a conventional imaging modality such as CT because IVL rarely forms massive extravascular lesions. FDG‐PET can be useful to uncover pulmonary IVL despite normal findings by a chest CT scan in cases of suspected lymphoma.2

CONFLICT OF INTEREST

The authors have stated explicitly that there are no conflicts of interest in connection with this article.