Cutaneous and Vascular Deposits of 18F-NaF by PET/CT in the Follow-Up of Patients with Pseudoxanthoma Elasticum.

Active microcalcification of elastic fibers is a hallmark of pseudoxanthoma elasticum and it can be measured with the assessment of deposition of 18F-NaF using a PET/CT scan at the skin and vascular levels. It is not known whether this deposition changes over time in absence of specific therapy. We repeated in two years a PET/CT scan using 18F-NaF as a radiopharmaceutical in patients with the disease and compared the deposition at skin and vessel. Furthermore, calcium score values at the vessel wall were also assessed. Main results indicate in the vessel walls that calcification progressed in each patient; by contrast, the active microcalcification, measured and target-to-background ratio showed reduced active deposition. By contrast, at skin levels (neck and axillae) the uptake of the pharmaceutical remains unchanged. In conclusion, because calcification in the arterial wall is not specific for pseudoxanthoma elasticum condition, the measurement of the deposition of 18F-NaF in the neck might be potentially used as a surrogate marker in future trials for the disease.

Orbital nerve seath myxoma with extraocular muscle involvement: a rare case.

A 66-year-old woman with breast cancer presented with a painless mass in the left orbit. MRI revealed a well-defined intraconal mass in the temporal quadrant of the orbit. Fifteen months later, a further MRI indicated the mass had grown, displacing the left optic nerve and making contact with the lateral rectus muscle, suggesting its possible intramuscular origin. Despite the clinical and radiological characteristics of the lesion and its slow growth, a PET/CT study was developed because of the history of malignant disease. No metabolic activity of the mass or malignant lesion in other locations was observed. After surgical excision, histopathological examination revealed an abundant myxoid matrix with few spindle-shaped cells and no signs of malignancy. The cells were immunopositive for CD34, positive for S-100 protein, and negative for EMA, actin, and CD57. A diagnosis was made of a nerve sheath myxoma. The orbital location of these tumors is extremely rare.