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Clinicopathological and imaging features of pulmonary alveolar microlithiasis in a dog - a case report
Ana Canadas Sousa1, Joana C Santos2, Clara Landolt2
1Department of Molecular Pathology and Immunology, Veterinary Pathology Laboratory, Institute of Biomedical Sciences Abel Salazar - University of Porto (ICBAS-UP), Rua Jorge Viterbo Ferreira 228, 4050-31, Porto, Portugal.
Background:
The aetiology of pulmonary alveolar microlithiasis (PAM) in animals is still unknown. In humans, this pulmonary disorder is a rare autosomal recessive disorder triggered by a mutation in the gene SLC34A2, which causes deposition and aggregation of calcium and phosphate in the pulmonary parenchyma with formation of microliths. Although histopathological examination is required for a definite diagnosis, in humans, imaging modalities such as computed tomography can demonstrate typical patterns of the disease. This is the first description of the computed tomographic (CT) features of a histologically confirmed PAM in dogs.
Case Presentation:
The following report describes a case of a 7-year-old female Boxer dog evaluated for paroxysmal loss of muscle tone and consciousness with excitement. The main differential diagnoses considered were syncope, seizures, and narcolepsy-cataplexy. The results of the complete blood count, serum biochemistry panel, urinalysis, arterial blood pressure, echocardiography, abdominal ultrasound, Holter monitoring, and ECG were all within normal limits. Additional exams included thoracic radiographs, head and thorax CT, bronchoalveolar lavage (BAL), and CT-guided cytology. Thoracic radiographs revealed micronodular calcifications in the lungs, with sandstorm appearance. Computed tomography of the thorax showed the presence of numerous mineralized high-density agglomerates of multiple sizes throughout the pulmonary parenchyma, a reticular pattern with ground glass opacity and intense mineralized fibrosis of the pleural lining. Head CT was unremarkable. BAL and CT-guided cytology were inconclusive, but imaging features strongly suggest the diagnosis of PAM, which was histologically confirmed after necropsy.
Conclusions:
This case report contributes to the clinicopathological and imaging characterization of pulmonary alveolar microlithiasis in dogs. In this species, the diagnosis of PAM should be considered when CT features evidence a reticular pattern with ground glass opacity and the presence of an elevated number and size of calcifications.
Insights
Pulmonary alveolar microlithiasis (PAM) in dogs is characterized by lung calcifications. Computed tomography (CT) reveals a reticular pattern with ground glass opacity, aiding diagnosis when other tests are inconclusive.
Area of Science:
- Veterinary Radiology
- Pulmonary Pathology
- Canine Medicine
Background:
- Pulmonary alveolar microlithiasis (PAM) is a rare lung disorder caused by calcium and phosphate deposition.
- In humans, PAM is an autosomal recessive condition linked to SLC34A2 gene mutations.
- This report details the first computed tomographic (CT) findings of histologically confirmed PAM in a dog.
Observation:
- A 7-year-old female Boxer presented with episodic loss of muscle tone and consciousness.
- Initial diagnostics including bloodwork, ECG, and ultrasound were normal.
- Thoracic radiographs showed a "sandstorm" appearance of micronodular calcifications.
Findings:
- Thoracic CT revealed widespread, multifocal mineralized nodules, a reticular pattern with ground glass opacity, and pleural fibrosis.
- Head CT, bronchoalveolar lavage, and CT-guided cytology were inconclusive.
- Histological confirmation post-necropsy established the diagnosis of PAM.
Implications:
- This case expands the understanding of PAM's clinicopathological and imaging features in canines.
- CT findings of a reticular pattern with ground glass opacity and extensive calcifications are key diagnostic indicators for canine PAM.
- This study highlights the importance of advanced imaging in diagnosing rare pulmonary diseases in veterinary medicine.
