Fulminant pulmonary calcification complicating renal transplantation: CT demonstration

Metastatic pulmonary calcifications after pediatric liver transplantation

BACKGROUND

Pulmonary calcification (PC) is a rare clinical entity observed following liver transplantation (LT). Most often identified in adults or in patients with concomitant renal failure, PC is rarely reported in children. While the clinical course of PC is largely benign, cases of progressive respiratory failure and death have been reported. Additionally, PC may mimic several other disease processes making diagnosis and management challenging. Currently, little is reported regarding the diagnosis, management, and long-term outcomes of children with PC following LT.

METHODS

We performed a retrospective chart review of patients undergoing LT at our institution between 2006 and 2023. We identified two patients who developed PC following LT. Their diagnosis, clinical course, and long-term outcomes are reported. A literature review of the presentation, diagnosis, management, and outcomes of adult and pediatric patients with PC post-LT was also performed.

CONCLUSIONS

Pulmonary calcifications are a rare but notable complication after pediatric liver transplantation. Our case series adds to the limited literature on this clinical entity in children but also highlights the fact that effective diagnosis and treatment may be safely accomplished without the use of lung biopsy.

Metastatic Pulmonary Calcification: Single-Center Review of Typical and Atypical Imaging Features

PURPOSE

The purpose of this study is to bring attention to an atypical form of metastatic pulmonary calcification, which is conventionally described as a metabolic process with upper lobe predominance in patients with a specific clinical history, which has not been reported as a distinct entity.

METHODS

Patients with metastatic pulmonary calcification (MPC) were first identified with mPower keyword search, including MPC or metastatic calcifications on computed tomography chest radiological reports. Patients were then filtered on likelihood of MPC based off imaging reports. Images were then reviewed by three senior radiologists for pertinent characteristics such as location of MPC, degree of calcifications and pleural effusions. Based on the predominant location of MPC, cases were labeled as either typical or atypical. Clinical and imaging characteristics relevant to MPC were noted and compared across typical and atypical cases.

RESULTS

In our study, we describe 25 patients with MPC, 13 defined as typical MPC and 12 with atypical MPC. Through consensus of senior radiologists, MPC was deemed to be mild (52%), moderate (44%), or severe (4%). Twenty-three patients (92%) had underlying renal disease including 21 requiring dialysis at the time of diagnosis. Outside of age at diagnosis, there was no significant clinical difference between the two groups. Evaluation of imaging characteristics (average HU attenuation, 267; range, 186-295), pattern and distribution of calcification, and clinical history strongly supported a diagnosis of atypical MPC.

CONCLUSION

This study presents several cases of lower lobe subpleural MPC associated with pleural effusions, which has not been reported as a distinct entity, despite comprising a significant portion of MPC cases at our institution.

Stepwise diagnostic algorithm for high-attenuation pulmonary abnormalities on CT

High-attenuation pulmonary abnormalities are commonly seen on CT. These findings are increasingly encountered with the growing number of CT examinations and the wide availability of thin-slice images. The abnormalities include benign lesions, such as infectious granulomatous diseases and metabolic diseases, and malignant tumors, such as lung cancers and metastatic tumors. Due to the wide spectrum of diseases, the proper diagnosis of high-attenuation abnormalities can be challenging. The assessment of these abnormal findings requires scrutiny, and the treatment is imperative. Our proposed stepwise diagnostic algorithm consists of five steps. Step 1: Establish the presence or absence of metallic artifacts. Step 2: Identify associated nodular or mass-like soft tissue components. Step 3: Establish the presence of solitary or multiple lesions if identified in Step 2. Step 4: Ascertain the predominant distribution in the upper or lower lungs if not identified in Step 2. Step 5: Identify the morphological pattern, such as linear, consolidation, nodular, or micronodular if not identified in Step 4. These five steps to diagnosing high-attenuation abnormalities subdivide the lesions into nine categories. This stepwise radiologic diagnostic approach could help to narrow the differential diagnosis for various pulmonary high-attenuation abnormalities and to achieve a precise diagnosis.Critical relevance statement Our proposed stepwise diagnostic algorithm for high-attenuation pulmonary abnormalities may help to recognize a variety of those high-attenuation findings, to determine whether the associated diseases require further investigation, and to guide appropriate patient management. Key points • To provide a stepwise diagnostic approach to high-attenuation pulmonary abnormalities.• To familiarize radiologists with the varying cause of high-attenuation pulmonary abnormalities.• To recognize which high-attenuation abnormalities require scrutiny and prompt treatment.

Update on imaging in chronic kidney disease-mineral and bone disorder: promising role of functional imaging

Disorders of mineral metabolism and bone disease are common complications in chronic kidney disease (CKD) patients and are associated with increased morbidity and mortality. Bone biopsies, bone scintigraphy, biochemical markers, and plain films have been used to assess bone disorders and bone turnover. Of these, functional imaging is less invasive than bone/marrow sampling, more specific than serum markers and is therefore ideally placed to assess total skeletal metabolism. ¹⁸F-sodium fluoride (NaF) PET/CT is an excellent bone-seeking agent superior to conventional bone scan in CKD patients due to its high bone uptake, rapid single-pass extraction, and minimal binding to serum proteins. Due to these properties, ¹⁸F-NaF can better assess the skeletal metabolism on primary diagnosis and following treatment in CKD patients. With the increased accessibility of PET scanners, it is likely that PET scanning with bone-specific tracers such as ¹⁸F-NaF will be used more regularly for clinical assessment and quantitation of bone kinetics. This article describes the pattern of scintigraphic/functional appearances secondary to musculoskeletal alterations that might occur in patients with CKD.

Metastatic pulmonary calcification: First report of pulmonary calcium suppression using dual-energy CT

Metastatic pulmonary calcification is an underdiagnosed metabolic lung disease characterized by diffuse calcium deposition in the lungs, often associated with secondary hyperparathyroidism due to chronic renal failure. A 31-year-old man with chronic renal failure initially presented with diffuse pain symptoms, deterioration of general condition, and respiratory insufficiency. Noncontrast-enhanced computed tomography of the chest was performed using a spectral-detector-based dual-energy CT. It showed multiple, centrilobular, ground-glass opacities, and nodules, ultimately leading to the diagnosis. Calcium suppression proved to be highly useful to classify the pulmonary alterations.

Metastatic pulmonary calcification: high-resolution computed tomography findings in 23 cases

Objective

The aim of this study was to evaluate the high-resolution computed tomography (HRCT) findings in patients diagnosed with metastatic pulmonary calcification (MPC).

Materials and Methods

We retrospectively reviewed the HRCT findings from 23 cases of MPC [14 men, 9 women; mean age, 54.3 (range, 26-89) years]. The patients were examined between 2000 and 2014 in nine tertiary hospitals in Brazil, Chile, and Canada. Diagnoses were established by histopathologic study in 18 patients and clinical-radiological correlation in 5 patients. Two chest radiologists analyzed the images and reached decisions by consensus.

Results

The predominant HRCT findings were centrilobular ground-glass nodules (n = 14; 60.9%), consolidation with high attenuation (n = 10; 43.5%), small dense nodules (n = 9; 39.1%), peripheral reticular opacities associated with small calcified nodules (n = 5; 21.7%), and ground-glass opacities without centrilobular ground-glass nodular opacity (n = 5; 21.7%). Vascular calcification within the chest wall was found in four cases and pleural effusion was observed in five cases. The abnormalities were bilateral in 21 cases.

Conclusion

MPC manifested with three main patterns on HRCT, most commonly centrilobular ground-glass nodules, often containing calcifications, followed by dense consolidation and small solid nodules, most of which were calcified. We also described another pattern of peripheral reticular opacities associated with small calcified nodules. These findings should suggest the diagnosis of MPC in the setting of hypercalcemia.

Fulminant respiratory failure due to progressive metastatic pulmonary calcification with no predisposing factors after successful renal transplantation: A case report

We report the patient with MPC who developed fulminant respiratory failure that leads to death with no predisposing factors after successful renal transplantation. In addition to infectious diseases, MPC should be kept in mind when post-transplantation patients develop pulmonary symptoms. The majority of the patients with MPC are asymptomatic; however, some patients develop fulminant respiratory failure and may progress to death. MPC can develop or progress in patients with no predisposing factors after successful renal transplantation.

Uremic lung: The "calcified cauliflower" sign in the end stage renal disease

Metastatic pulmonary calcification (MPC) is a rare pathological condition consisting of lung calcium salt deposits which commonly occurs in patients affected by chronic kidney disease probably for some abnormalities in calcium and phosphate metabolism. CT represents the technique of choice for detecting MPC findings including ground glass opacities and partially calcified nodules or consolidations. We present a case of MCP in a patient affected by hepato-renal autosomic-dominant polycystic disease; chest CT revealed extensive lobar-segmental parenchymal calcification with a peculiar cauliflower shape which we called “calcified cauliflower” sign. The “calcified cauliflower” sign can be reported as a new CT pattern of uremic lung that needs to be identified for a correct diagnosis and patient management.

Presurgical pulmonary evaluation in renal transplant patients

Patients with chronic renal failure (CRF) due to various mechanisms are prone to significant pulmonary comorbidities. With the improvements in renal replacement therapy (RRT), patients with CRF are now expected to live longer, and thus may develop complications in the lung from these processes. The preferred treatment of CRF is kidney transplantation and patients who are selected to undergo transplant must have a thorough preoperative pulmonary evaluation to assess pulmonary status and to determine risk of postoperative pulmonary complications. A MEDLINE^®/PubMed^® search was performed to identify all articles outlining the course of pre-surgical pulmonary evaluation with an emphasis on patients with CRF who have been selected for renal transplant. Literature review concluded that in addition to generic pre-surgical evaluation, renal transplant patients must also undergo a full cardiopulmonary and sleep evaluation to investigate possible existing pulmonary pathologies. Presence of any risk factor should then be aggressively managed or treated prior to surgery.

Metastatic pulmonary calcification: state-of-the-art review focused on imaging findings

Metastatic pulmonary calcification (MPC) is a subdiagnosed metabolic lung disease that is commonly associated with end-stage renal disease. This interstitial process is characterized by the deposition of calcium salts predominantly in the alveolar epithelial basement membranes. MPC is seen at autopsy in 60-75% of patients with renal failure. It is often asymptomatic, but can potentially progress to respiratory failure. Chest radiographs are frequently normal or demonstrate confluent or patchy airspace opacities. Three patterns visible on high-resolution computed tomography have been described: multiple diffuse calcified nodules, diffuse or patchy areas of ground-glass opacity or consolidation, and confluent high-attenuation parenchymal consolidation. The relative stability of these pulmonary infiltrates, in contrast to infectious processes, and their resistance to treatment, in the clinical context of hypercalcemia, are of diagnostic value. Scintigraphy with bone-seeking radionuclides may demonstrate increased radioactive isotope uptake. The resolution of pulmonary calcification in chronic renal failure may occur after parathyroidectomy, renal transplantation, or dialysis. Thus, the early diagnosis of MPC is beneficial. The aim of this review is to describe the main clinical, pathological, and imaging aspects of MPC.

Metabolic and storage lung diseases: spectrum of imaging appearances

Metabolic and storage diseases constitute a heterogeneous group of disorders that occur in the setting of altered biochemical homeostasis. Many of these disorders affect the lungs, either exclusively or as part of a systemic syndrome. For example, amyloidosis can be limited to the tracheobronchial tree or involve the kidneys, lungs and heart. The indolent course of some of these disorders and the non-specific clinical symptoms often result in a diagnostic challenge. Imaging, particularly high-resolution computed tomography (HRCT), is an invaluable asset in the diagnosis of these clinical conditions. Some metabolic and storage diseases have characteristic HRCT appearances, helping narrow the differential diagnosis. Correlation of the radiological and histopathological findings of this group of diseases has also helped improve understanding of these disorders. In addition, CT can offer guidance when tissue sampling is warranted and aid in histopathological diagnosis. This article describes the pertinent clinical features of the more common metabolic and storage diseases affecting the lungs, illustrates their respective HRCT findings and provides the relevant differential diagnosis.

TEACHING POINTS

• To recognise the various metabolic and storage lung diseases • To identify the characteristic imaging findings in various metabolic and storage lung diseases • To discuss the relevant differential diagnoses of each of these diseases.

Aggressive pulmonary calcification developed after living donor kidney transplantation in a patient with primary hyperparathyroidism

Metastatic pulmonary calcification, defined as calcium deposition in the intact lung, is commonly seen in patients with chronic renal failure, and it is known to be a benign clinical condition when detected by chance in an asymptomatic patient. Here we report the case of a 33-year-old woman who developed rapid and aggressive metastatic pulmonary calcification shortly after a living donor kidney transplantation, which induced acute antibody-mediated rejection. The patient's metastatic pulmonary calcification was successfully improved by extensive treatment for graft rejection, the correction of her accompanying primary hyperparathyroidism, and medical treatment with a bisphosphonate and sodium thiosulfate. Aggressive pulmonary calcification is reported as a rare complication seen in patients who have undergone a failed renal transplantation. A failed renal graft and accompanying secondary hyperparathyroidism seem to accelerate metastatic calcification. Most of the patients who develop aggressive pulmonary calcification suffer from the rapid progression of dyspnea and occasionally fever, and they die of respiratory failure. Pulmonary calcification should be considered in a patient developing dyspnea and unexplained pulmonary infiltrate, especially in the context of renal graft rejection; otherwise the prognosis of the patient will be very poor.

Metastatic pulmonary calcification in multiple myeloma in a 45-year-old man

Metastatic calcification has been associated with multiple-myeloma-induced hypercalcemia. Despite of a relatively high prevalence of metastatic pulmonary calcification in patients with multiple myeloma, only a few cases have been clinically and radiologically detected. A 45-year-old Hispanic male presented to the Emergency Department with complaint of worsening weakness and myalgia. Laboratory findings revealed renal insufficiency and hypercalcemia. CT scan of chest revealed calcified pleural and pulmonary nodule. Technetium (Tc) 99 bone scan revealed diffuse activity in the pulmonary parenchyma consistent with metastatic pulmonary calcification. Metastatic pulmonary calcification, despite its high prevalence, remains undetected. This is, in part, due to its radiographic characteristic properties that evade detection by routine imaging studies. We present a case of a metastatic pulmonary calcification in a patient diagnosed with multiple myeloma and chronic kidney disease, as well as a brief literature review including clinical findings and treatment options.

[Pulmonary metastatic calcification]

INTRODUCTION

The lung is the organ most frequently involved by metastatic calcification. This condition is probably under-diagnosed, the patients usually being asymptomatic. This article summarizes the current knowledge concerning pulmonary metastatic calcification.

BACKGROUND

The pathogenesis of pulmonary metastatic calcification is not well known, but it involves phosphate-calcium balance, renal function and pH. The most frequently encountered aetiologies are hyperparathyroidism, neoplastic bony lesions, and renal failure. The definitive diagnosis is achieved by histology, radiological examinations being insensitive. The clinical manifestations are various and can include a pulmonary restrictive syndrome, diffusion abnormalities, hypoxaemia and respiratory failure. The latter can be severe and influence the prognosis adversely: 19 cases of fatal pulmonary metastatic calcification have been reported. The treatment is aetiological and symptomatic.

VIEWPOINT

The prognostic factors for a poor outcome of this potentially lethal condition remain to be determined. The management of asymptomatic patients is also uncertain.

CONCLUSIONS

Pulmonary metastatic calcification is a rare condition of complex pathogenesis. The clinical manifestations are varied, ranging from asymptomatic to severe, even fatal.

Metastatic pulmonary calcification in chronic renal failure

Metastatic pulmonary calcification can be caused by a number of diseases, most common being end-stage renal disease. Most of the patients are asymptomatic, and imaging with computed tomography is useful in making a diagnosis. Demonstration of pulmonary and chest wall vessel calcification is characteristic. We report a case of a 60-year-old patient with chronic renal failure on dialysis, presenting with gradual onset dyspnea, who showed metastatic pulmonary calcification on chest imaging.

Prevalence of radiological findings among cases of severe secondary hyperparathyroidism

CONTEXT AND OBJECTIVE

Patients with end stage renal disease (ESRD) and secondary hyperparathyroidism (HPT2) are prone to develop heterotopic calcifications and severe bone disease. Determination of the sites most commonly affected would decrease costs and patients' exposure to X-ray radiation. The aim here was to determine which skeletal sites produce most radiographic findings, in order to evaluate hemodialysis patients with HPT2, and to describe the most prevalent radiographic findings.

DESIGN AND SETTING

This study was cross-sectional, conducted in one center, the Hospital Universitário Clementino Fraga Filho (HUCFF), in Rio de Janeiro, Brazil.

METHODS

Whole-body radiographs were obtained from 73 chronic hemodialysis patients with indications for parathyroidectomy due to severe HPT2. The regions studied were the skull, hands, wrists, clavicles, thoracic and lumbar column, long bones and pelvis. All the radiographs were analyzed by the same two radiologists, with great experience in bone disease interpretation.

RESULTS

The most common abnormality was subperiosteal bone resorption, mostly at the phalanges and distal clavicles (94% of patients, each). 'Rugger jersey spine' sign was found in 27%. Pathological fractures and deformities were seen in 27% and 33%, respectively. Calcifications were presented in 80%, mostly at the forearm fistula (42%), abdominal aorta and lower limb arteries (35% each). Brown tumors were present in 37% of the patients, mostly on the face and lower limbs (9% each).

CONCLUSION

The greatest prevalence of bone findings were found on radiographs of the hands, wrists, lateral view of the thoracic and lumbar columns and femurs. The most prevalent findings were bone resorption and ectopic calcifications.

Noninfectious Pulmonary Complications of Liver, Heart, and Kidney Transplantation

Because of their chronically immunosuppressed status, solid organ transplant recipients are continually at risk for infectious pulmonary complications. In addition, however, a number of noninfectious pulmonary complications plague the transplant recipient. These complications arise because of numerous factors, including the underlying conditions that preceded transplantation, the transplant surgery itself, and toxicity of post-transplantation medications. This article focuses on noninfectious pulmonary complications in the three largest recipient populations: liver, kidney, and heart.

Pulmonary Complications of Transplantation: Radiographic Considerations

The aim of this article is to clarify radiographic definitions associated with common parenchymal patterns encountered in the transplant population and to discuss the most common pathologic causes responsible for each pattern. The article also touches on radiographic findings signifying complications of other intrathoracic structures, including the airways, pleural space, and mediastinum.

[Diffuse pulmonary calcification in a patient with renal insufficiency]

We report the case of a 37-year-old man with chronic renal insufficiency, on hemodialysis, with no respiratory symptoms but whose chest radiograph showed parenchymal consolidation in the middle and upper lung fields. High resolution computed tomography showed a high-attenuating diffuse alveolar pattern that indicated calcium deposits. Bronchoscopy revealed metastatic calcification on the interalveolar septa and bronchiolar and arteriolar. The present report, based on radiologic and bronchoscopic findings, describes the pathogenesis and anatomical distribution of the patient's diffuse pulmonary calcification.

Imaging of diffuse metastatic and dystrophic pulmonary calcification in children after haematopoietic stem cell transplantation

The authors describe three cases of diffuse pulmonary calcification; two metastatic in children with acute transitory renal failure and the other dystrophic in a child with leukaemia. All three patients underwent haematopoietic stem cell transplantation (HSCT). Chest radiographs disclosed diffuse calcification within the lungs. The distribution of this calcification was bilateral but asymmetric. Diagnosis was made in two cases by high resolution computed tomography (HRCT) and in one case by HRCT and bone scan. Radiological characteristics, scintigraphic features, pathological mechanism and clinical outcome of such pulmonary calcification are discussed.

Unusual Manifestations of Metastatic Pulmonary Calcification

The aim of this report is to describe the high-resolution CT and pathologic findings of 3 patients with unusual manifestations of metastatic pulmonary calcification. These include a case that presented with extensive dense consolidation, a case of metastatic calcification that improved spontaneously, and a case of metastatic calcification in a patient with no demonstrable biochemical abnormality or underlying disease. We conclude that metastatic calcification may present with dense bilateral consolidation, may improve spontaneously, and may rarely present in patients with no apparent underlying biochemical abnormality.

Pulmonary complications of solid organ and hematopoietic stem cell transplantation

The ability to successfully transplant solid organs and hematopoietic stem cells represents one of the landmark medical achievements of the twentieth century. Solid organ transplantation has emerged as the standard of care for select patients with severe vital organ dysfunction and hematopoietic stem cell transplantation has become an important treatment option for patients with a wide spectrum of nonmalignant and malignant hematologic disorders, genetic disorders, and solid tumors. Although advances in surgical techniques, immunosuppressive management, and prophylaxis and treatment of infectious diseases have made long-term survival an achievable goal, transplant recipients remain at high risk for developing a myriad of serious and often life-threatening complications. Paramount among these are pulmonary complications, which arise as a consequence of the immunosuppressed status of the recipient as well as from such factors as the initial surgical insult of organ transplantation, the chemotherapy and radiation conditioning regimens that precede hematopoietic stem cell transplantation, and alloimmune mechanisms mediating host-versus-graft and graft-versus-host responses. As the population of transplant recipients continues to grow and as their care progressively shifts from the university hospital to the community setting, knowledge of the pulmonary complications of transplantation is increasingly germane to the contemporary practice of pulmonary medicine.

Calcium deposition with or without bone formation in the lung

Pulmonary calcification and ossification occurs with a number of systemic and pulmonary conditions. Specific symptoms are often lacking, but calcification may be a marker of disease severity and its chronicity. Pathophysiologic states predisposing to pulmonary calcification and ossification include hypercalcemia, a local alkaline environment, and previous lung injury. Factors such as enhanced alkaline phosphatase activity, active angiogenesis, and mitogenic effects of growth factors may also contribute. The clinical classification of pulmonary calcification includes both metastatic calcification, in which calcium deposits in previously normal lung or dystrophic calcification, which occurs in previously injured lung. Pulmonary ossification can be idiopathic or can result from a variety of underlying pulmonary, cardiac, or extracardiopulmonary disorders. The diagnosis of pulmonary calcification and ossification requires various imaging techniques, including chest radiography, computed tomographic scanning, and bone scintigraphy. Interpretation of the presence of and the specific pattern of calcification or ossification may obviate the need for invasive biopsy. In this review, specific conditions causing pulmonary calcification or ossification that may impact diagnostic and treatment decisions are highlighted. These include metastatic calcification caused by chronic renal failure and orthotopic liver transplantation, dystrophic calcification caused by granulomatous disorders, DNA viruses, parasitic infections, pulmonary amyloidosis, vascular calcification, the idiopathic disorder pulmonary alveolar microlithiasis, and various forms of pulmonary ossification.

Case report. Metastatic pulmonary calcification in renal failure: a new HRCT pattern

A 56-year-old male with chronic renal failure presented with a 6 month history of progressive dyspnoea. High resolution CT of the chest showed multiple, peripheral, centrilobular nodules in the upper and mid zones, consistent with metastatic pulmonary calcification. Some of these pulmonary nodules showed ring calcification, a pattern that to our knowledge has not been described before. Calcification was also seen in the segmental pulmonary arteries, bronchi, trachea and subcutaneous vessels of the chest wall.

Thoracic complications in uremic patients and in patients undergoing dialytic treatment: state of the art

No organ in the chest is spared the negative effects of uremia. The dialytic treatment itself is often associated with a large array of thoracic complications. We review the main thoracic manifestations of the terminal uremia from the radiological point of view, such as: uremic pleuritis and pericarditis, uremic pneumonia, renal osteodystrophy, infections, and metastatic pulmonary calcifications. Respiratory function derangement and the problems related to peritoneal dialysis and hemodialysis are discussed in some detail, along with the diagnostic role of plain films, US, nuclear medicine, and CT. The main focus of this review is on the hydration problems and pulmonary edema, often related to a large number of pathogenetic factors. Based on our experience, we think that the chest X-ray is not able to accurately discriminate between cardiogenic edema and fluid overload edema (so-called renal pulmonary edema). The radiological findings of the thoracic complications in uremic patients are multiple and complex but, in most cases, the imaging techniques may offer an accurate and noninvasive diagnostic approach, with a high benefit-cost ratio.

MR appearance of pulmonary metastatic calcification

We report a case of metastatic pulmonary calcification that showed hyperintense signal on T1-weighted MRI. This uncommon MR appearance of calcification is similar to the MR characteristics of calcification in the brain due to abnormal calcium metabolism.

Localised pulmonary metastatic calcification associated with pulmonary artery obstruction

BACKGROUND

Metastatic pulmonary calcification, a complication of uraemia and disordered calcium metabolism, may be diffuse or localised. The factors that determine calcium precipitation are complex, but tissue alkalosis is thought to be important. As obstruction of the pulmonary artery theoretically causes local alkalosis a retrospective necropsy study was carried out to examine the relation between metastatic pulmonary calcification and vascular obstruction.

METHODS

Five patients with focal and two with diffuse metastatic calcification in the lungs were identified over eight years. Lungs were studied macroscopically and by light microscopy, haematoxylin and eosin and histochemical stains being used for calcium.

RESULTS

Underlying risk factors for calcification in these patients included renal failure in six and disseminated malignancy in five. In the five patients with localised calcification obstruction of the pulmonary artery by thrombus or tumour was found proximal or adjacent to areas of calcium deposition. In two patients metastatic calcification was confined to a lung with unilateral pulmonary artery thromboembolic occlusion. Calcification was not specifically associated with infarction, pneumonia, or diffuse alveolar damage. Lesions of the pulmonary artery were not seen in the two patients with diffuse bilateral metastatic calcification.

CONCLUSION

In this small series there was a spatial association between pulmonary artery obstruction and localised metastatic calcification. It is proposed that pulmonary artery obstruction alters the microchemical environment of the lung, favouring tissue alkalosis and thereby enhancing parenchymal calcification in patients predisposed to this condition.