Aluminium and injection site reactions

To alert pathologists to the spectrum of histological appearances that may be seen in injection site reactions related to aluminium.

Four cases of injection site reaction were examined microscopically using routine staining with haematoxylin and eosin, electron microscopy and by electron probe microanalysis.

As in previous reports, all four cases included collections of histiocytes which contained faint granular brownish refractile material within their cytoplasm; ultrastructural examination showed this to be aluminium. Two cases showed a prominent inflammatory reaction with numerous lymphoid follicles and a notable eosinophilic infiltrate. Two cases showed unusual features not described previously. In one, there was a sclerosing lipogranuloma-like reaction with unlined cystic spaces containing crystalline material. The other case presented as a large symptomatic subcutaneous swelling which microscopically showed diffuse and wide-spread involvement of the subcutis by a lymphoid infiltrate with prominent lymphoid follicles.

This report highlights the changes encountered in aluminium injection site reactions and emphasises that the lesions have a wider range of histological appearances than described previously.