Marc De Bonte

Allergic contact granuloma due to palladium following ear piercing

Two cases of sarcoidal‐type allergic contact granuloma due to metals in ear piercing are presented, the first to palladium (Pd) only, and the second to Pd and possibly also to other metals. Both the patients developed papulonodular lesions at the helices following ear piercing, which after 3–4 weeks, became more granulomatous and very resistant to treatment. Indeed, repeated intralesional injections with corticosteroids produced only a temporary regression of the lesions. Biopsies from the persistent granulomatous lesions from the helices in both the patients and the positive test to Pd in case 2, 3 weeks after the patch‐testing procedure, demonstrated epithelioid granulomas, with some multinucleate histiocytes surrounded by a lymphocytic–histiocytic infiltrate. Areas of fibrinoid necrosis were found in both the helix biopsies. An infectious pathology was excluded. Patch testing showed a strong positive reaction to Pd only in case 1 and to Pd and nickel in case 2. Chemical analysis of the earring of patient 1 confirmed the presence of Pd; however, analysis of the earrings of the second patient did not show the presence of Pd, but showed the presence of nickel and copper. Both the clinical and histological findings concur with some rarely reported similar observations in the literature.

Reactivity in the chromium oxide-calcium fluoride system: An empirical approach

The reaction mechanisms observed when sintering loose Cr 2 O 3 –CaF 2 powder mixtures were analyzed, and the influence of the sintering parameters on the reaction behavior is presented. Using x-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and differential thermal analysis (DTA) measurements, CaCrO4 was shown to be the reaction product when sintering in air. The reaction occurs in two steps: CaF 2 transforms to CaO at the Cr 2 O 3 –CaF 2 interface, followed by a CaO–Cr 2 O 3 interaction, which creates the reaction product. Scanning electron microscopy (SEM) and x-ray fluorescence (XRF) analysis showed an increasing loss of CaF 2 with increasing sintering temperature and heating rate, while an opposite evolution of the amount of reaction product was observed.