Calcium oxalate precipitates in a renomedullary interstitial cell tumor

Potential clinical implications of an incidental renomedullary interstitial cell tumor in renal allograft biopsy

Renomedullary interstitial cell tumors (RMICTs) are often incidentally detected lesions at autopsy or resection of the kidney for other reasons. The RMICTs have not been reported in renal allograft biopsy. Overall, given the clinical implications of the differential diagnosis considered, such as morphologically similar neoplasms, interstitial fibrosis and tubular atrophy (IFTA), amyloidosis, and oxalosis, it is prudent to exclude these by an appropriate workup. Once excluded, the patients can be reassured. However, regular follow-up is recommended due to the propensity of RMICT to increase in size with age.

Pulmonary dystrophic oxalosis and its possible relation to fibrosis in an aged Gentoo penguin (Pygoscelis papua)

A 20-year-old Gentoo penguin was found dead with a clinical history of inappetence and dyspnoea. At necropsy, the lungs showed severe congestion/hemorrhage and atelectasis. Histopathologically, fibrosis was observed exclusively around parabronchi with severe collagen deposition. In fibrotic lesions, there were numerous depositions of crystalline structures accompanied by epithelioid cells and multinucleated giant cells (foreign body type). In addition to irregularly lamellar structures as the morphology, the crystals were demonstrated calcium oxalate (CaOx) by the Alizarin red S staining with and without polarized light and von Kossa's staining. Myocobacteria and fungi were not found by special and immuohistochemical stainings. Pulmonary dystrophic oxalosis is a very rare lesion in Gentoo penguin.

Atherosclerotic oxalosis in coronary arteries

BACKGROUND

Systemic oxalosis may be hereditary or acquired. In these cases, calcium oxalate deposits have been reported in numerous tissues, including the media of arteries. In any category, calcium oxalate deposition has not been described within atherosclerotic plaques in any arteries.

METHODS

As part of a retrospective clinicopathologic study, 80 hearts were obtained from the National Neurological AIDS Bank in an effort to study coronary atherosclerosis in patients infected with HIV. The population consisted of 66 HIV-positive and 14 HIV-negative patients with an average age of 47 years; 79% were males. Proximal coronary arteries were serially sectioned and processed routinely. Sections were studied by hematoxylin and eosin staining and, in selected cases, von Kossa stain and alizarin red S under different conditions, including polarized light, to allow distinction of calcium phosphate from calcium oxalate. Medical histories, autopsy reports, and general autopsy slides were reviewed.

RESULTS

In four patients (three with AIDS), calcium oxalate crystals were observed within atherosclerotic plaques in the coronary arteries. Similar deposits were seen in the thyroid gland and other organs but not in the kidneys. None of the patients had chronic renal failure.

CONCLUSION

The calcium oxalate crystal deposits observed in the atherosclerotic plaques in the coronary arteries of these four patients are unique in two ways: (a) these deposits have not previously been described in atherosclerotic plaques; (b) the patients did not demonstrate any of the recognized patterns of oxalosis. We suggest the phrase "atherosclerotic oxalosis" to describe this finding.