Metastatic pulmonary calcification on bone scintigraphy of a patient with lupus nephritis and end-stage renal disease

Our plain-English summary of Metastatic pulmonary calcification on bone scintigraphy of a patient with lupus nephritis and end-stage renal disease, by N.H. Cheng, Y. Li, G. Cheng (Radiology Case Reports, 2023).

The study

• Authors: N.H. Cheng, Y. Li, G. Cheng
• Journal: Radiology Case Reports
• Published: 2023;18(11):3993-3996
• Type of article: Case report
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A 65-year-old male complaining of low back pain was noted to have diffuse, homogenous bilateral lung uptake on Tc-99m methylene diphosphate (Tc99m-MDP) bone scintigraphy. The patient had no prior history of pulmonary disease with no apparent respiratory symptoms at time of imaging, but did endorse a long history of lupus nephritis and end-stage renal disease on hemodialysis. Review of prior chest CT and chest X-ray imaging over the last 5 years revealed diffuse ground-glass opacities and extensive parenchymal calcifications, consistent with metastatic pulmonary calcification. These radiological findings were further corroborated by laboratory studies, which demonstrated longstanding secondary hyperparathyroidism with a most recent work-up including an iPTH level of 1251 pg/mL. The differential diagnosis of bilateral, diffuse Tc99m-MDP uptake on bone scintigraphy includes tracer contamination, pulmonary etiologies such as pleural effusion or mesothelioma, metabolic diseases such as metastatic pulmonary calcification, and genetic diseases including pulmonary alveolar microlithiasis. In the setting of longstanding renal dysfunction and chronic hypercalcemia as in this patient, such radiological findings are a classic presentation of metastatic pulmonary calcification.

Published by Elsevier Inc. on behalf of University of Washington.

In plain English

This article was a case report about one patient. It did not mention asbestos. Mesothelioma appeared only in the abstract and discussion, as one possible cause of the scan pattern, not as this patient's diagnosis. A 65-year-old man had a whole-body bone scan with the tracer Tc99m-MDP to check hip and lower back pain. The scan showed even tracer uptake throughout both lungs. The patient had no apparent breathing symptoms. Checks confirmed that the intended tracer had been given and that he had not had a lung perfusion study before the bone scan. His earlier chest X-ray and chest CT showed hazy areas and widespread calcium deposits in the lungs, present on chest CT for at least 5 years. The authors identified these as metastatic pulmonary calcification. Despite the name, this means calcium deposits in the lung, not cancer spread. The patient had end-stage kidney disease, lupus-related kidney disease and 12 years of dialysis. His most recent parathyroid hormone level was 1251 pg/mL. The authors concluded that this calcification explained the lung uptake and that such uptake on a bone scan is not specific.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report
• Who was studied: One 65-year-old male patient with end-stage renal disease, lupus nephropathy and other conditions, imaged at a US medical center (Philadelphia affiliations). The imaging date is not given.
• Exposure: No asbestos or fiber exposure was described. The conditions examined were end-stage renal disease with secondary hyperparathyroidism and long-term hemodialysis. The patient received 28.6 mCi of Tc99m-MDP tracer for the bone scan.
• Main results:
  • The bone scan showed diffuse, homogeneous tracer uptake in both lungs of this patient.
  • Tracer contamination was ruled out: the patient had had no lung perfusion study before the bone scan, and radiopharmacy confirmed that the correct Tc99m-MDP tracer was given.
  • The patient had no apparent respiratory symptoms at the time of imaging.
  • Earlier chest X-ray and chest CT showed diffuse ground-glass opacities and extensive parenchymal calcifications. These were present on chest CT for at least 5 years.
  • The patient's most recent intact parathyroid hormone level was 1251 pg/mL (normal 10 to 55 pg/mL) and his eGFR was 9 mL/min. Serum creatinine had ranged from 4.5 to 10 mg/dL over the past 10 years.
  • In their discussion of other possible causes, the authors wrote that mesothelioma may show diffuse lung uptake on one side, and rarely on both sides. This was a general statement, not a finding in this patient.
• The authors' conclusion: The authors concluded that the diffuse, even lung uptake in this patient was due to diffuse calcification of lung tissue, a typical finding for metastatic pulmonary calcification. They also stated that lung uptake on a bone scan is not specific and must be compared with the patient's history and other imaging.

Topics

Medical terms in this study, explained in our Lexicon: Bilateral, Chest X-Ray, Differential Diagnosis, Pleural Effusion, Mesothelioma.

Related studies

• Asymmetrically increased rib cage uptake on bone scintigraphy: Incidental detection of pleural mesothelioma on single photon emission computed tomography/computed tomography — V.S. Dhull, P. Sharma, et al. (2014)
• 99mTc-HDP Bone Scintigraphy, SPECT/CT, and 18F-FDG PET/CT Diagnosis Imaging of Incidental Pleural Mesothelioma in a Patient With Biochemical Recurrences of Prostate Cancer: Is it Really a Coincidence? — P. Fernández-Rodríguez, J.J. Martín-Marcuartu, et al. (2020)
• Value of PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4 immunostaining in distinguishing pleural epithelioid mesothelioma from metastatic renal cell carcinoma — N.G. Ordóñez (2013)
• Metastatic renal cell carcinoma mimicking pleural mesothelioma — D.R. Taylor, W. Page, et al. (1987)
• The value of 'mesothelium-associated' antibodies in distinguishing between metastatic renal cell carcinomas and mesotheliomas — M. Osborn, N. Pelling, et al. (2002)
• Carbonic anhydrase IX is expressed in mesothelioma and metastatic clear cell renal cell carcinoma of the lung — M.L. Ramsey, B.J. Yuh, et al. (2012)

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