Description
A male patient in his early 70s presented with a 1-month history of progressive dyspnoea on exertion. His oxygen saturation was 94% on ambient air at rest but decreased to 82% when walking. Physical examination findings, including lung sounds, were normal. Laboratory tests revealed elevated serum lactate dehydrogenase at 752 U/L (reference: 124–222 U/L) and soluble interleukin-2 receptor at 1514 U/mL (reference: 122–496 U/mL). CT found no lung abnormalities (figure 1A), but 18F-fluorodeoxyglucose positron emission tomography (PET) CT revealed diffuse fluid accumulation in the bilateral lungs (figure 1B). A transbronchial lung biopsy performed in the right posterior regions (B2, B6, B9 and B10 segments) revealed CD3-negative and CD20-positive neoplastic lymphoid cells in the vessels (figure 2). Peripheral blood smears, a random skin biopsy and a bone marrow biopsy returned negative. Pulmonary intravascular large cell lymphoma was diagnosed. Following pola-R-CHP administration, his dyspnoea quickly resolved.
Figure 1.
(A) Chest CT revealed no lymphadenopathy or CT abnormality in the lung fields. (B) Despite the normal CT findings. 18F-fluorodeoxyglucose PET/CT revealed diffuse, bilateral, right predominant, accumulation in the lung field. PET, positron emission tomography.
Figure 2.
(A) H&E staining of a specimen from a transbronchial lung biopsy showing CD3-negative and CD20-positive neoplastic lymphoid cells lodged in the vessels (arrows). (B) CD20 immunohistochemical staining showing positivity of the lymphoid cells for CD20.
Intravascular large cell lymphoma (IVCL) is extremely difficult to diagnose because of its rarity (incidence: 0.095/1 000 000),1 non-specificity of its symptoms and potential for rapid deterioration.2 Lymphoma cells in IVCL proliferate exclusively within the vasculature, making a definitive, histological diagnosis challenging. Organs that may be biopsied include the skin, bone marrow, liver, kidney, brain, gastrointestinal tract and lungs, depending on the patient’s symptoms and tests results.2 Furthermore, if respiratory symptoms, including progressive dyspnoea, are present, PET/CT should be considered before a transbronchial biopsy.2
The so-called ‘hot lung sign’ is defined as a mismatch between PET/CT findings of accumulation and normal CT findings (table 1).3 Although the evidence is insufficient, most previously reported cases of hot lung sign were ultimately diagnosed as IVCL, making the sign a quasi-pathognomonic index of ILCL and a useful guide to determining the biopsy site.3 In our case, the 18F-fluorodeoxyglucose uptake was bilateral but more pronounced in the right posterior region; therefore, a targeted, transbronchial biopsy was performed at the site with successful results.
Table 1.
Hot lung sign in pulmonary intravascular large cell lymphoma
| Definition | A mismatch between PET/CT findings of accumulation and normal CT findings |
| CT findings | Normal or slightly abnormal findings, such as ground glass opacities and multiple, small nodules |
| PET/CT findings | Diffuse pulmonary 18F-fluorodeoxyglucose uptake in contrast to CT findings |
| Sensitivity/specificity | Data unavailable |
| Reported other conditions showing similar findings | Drug-induced pneumonitis,4 acute respiratory distress syndrome,5 granulomatosis with polyangiitis6 |
PET, positron emission tomography.
Learning points.
If respiratory symptoms, including progressive dyspnoea, are present in a patient with suspected intravascular large cell lymphoma (ILCL), positron emission tomography (PET)/CT should be considered before a transbronchial biopsy.
The ‘hot lung sign’, defined as a mismatch between PET/CT findings of accumulation and normal CT findings, is considered a quasi-pathognomonic index of ILCL and serves as a valuable guide for determining the biopsy site.
Footnotes
Contributors: The following authors were responsible for drafting of the text, sourcing and editing of clinical images, investigation results, drawing original diagrams and algorithms, and critical revision for important intellectual content: YK, HO and KM. The following authors gave final approval of the manuscript: HO and KM.
Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
Competing interests: None declared.
Provenance and peer review: Not commissioned; externally peer reviewed.
Ethics statements
Patient consent for publication
Consent obtained directly from patient(s).
References
- 1.Rajyaguru DJ, Bhaskar C, Borgert AJ, et al. Intravascular large B-cell lymphoma in the United States (US): a population-based study using surveillance, epidemiology, and end results program and National cancer database. Leuk Lymphoma 2017;58:1–9. 10.1080/10428194.2017.1287363 [DOI] [PubMed] [Google Scholar]
- 2.Ponzoni M, Campo E, Nakamura S. Intravascular large B-cell lymphoma: a chameleon with multiple faces and many masks. Blood 2018;132:1561–7. 10.1182/blood-2017-04-737445 [DOI] [PubMed] [Google Scholar]
- 3.Şahin Ö, Kaya B, Serdengeçti M, et al. Hot lung" sign in pulmonary Intravascular large B-cell lymphoma on 18F-FDG PET/CT. Clin Nucl Med 2020;45:e211–2. 10.1097/RLU.0000000000002939 [DOI] [PubMed] [Google Scholar]
- 4.Rodrigues RS, Miller PR, Bozza FA, et al. FDG-PET in patients at risk for acute respiratory distress syndrome: a preliminary report. Intensive Care Med 2008;34:2273–8. 10.1007/s00134-008-1220-7 [DOI] [PubMed] [Google Scholar]
- 5.Yamane T, Daimaru O, Ito S, et al. Drug-induced Pneumonitis detected earlier by 18F-FDG-PET than by high-resolution CT: a case report with non-Hodgkin’s lymphoma. Ann Nucl Med 2008;22:719–22. 10.1007/s12149-008-0183-7 [DOI] [PubMed] [Google Scholar]
- 6.Nelson DR, Johnson GB, Cartin-Ceba R, et al. Characterization of F-18 Fluorodeoxyglucose PET/CT in granulomatosis with polyangiitis. Sarcoidosis Vasc Diffuse Lung Dis 2016;32:342–52. [PubMed] [Google Scholar]