Giant congenital melanocytic nevus with cartilaginous differentiation.

We report the unusual presence of a benign focus of cartilage in an excised portion of giant congenital melanocytic nevus.

Composition and significance of splenic Gamna-Gandy bodies in sickle cell anemia.

Children with sickle cell anemia may undergo acute splenic sequestration. Splenectomy is performed in an attempt to reduce further events. Histologic studies of spleens have revealed the presence of granuloma-like nodules, known as Gamna-Gandy bodies with amorphous inclusions; however, their significance is unknown. The medical case records and histologic samples of consecutive children with sickle cell anemia treated with splenectomy between 2001 and 2007 at Our Lady's Children's Hospital, Dublin, were reviewed. Seventeen patients were identified. Gamna-Gandy bodies were studied by scanning electron microscopy and x-ray fluorescence spectroscopy. Gamna-Gandy bodies were identified in 7 (41%) patients, and amorphous inclusions were always seen. Patient age correlated significantly with Gamna-Gandy bodies (P = .002). Scanning electron microscopic analysis demonstrated the crystalline nature of Gamna-Gandy bodies and the chemical composition (C 47.1%; O(2) 29.7%; P 9.0%; K(+) 0.4%; Ca(2+) 6.4%; Fe(2+) 7.4%), whereas x-ray diffraction studied the structure (CaPO(4) ∙ FeOH). A crystal-formation gradient was observed, increasing from the red pulp to the white pulp. Our study shows that Gamna-Gandy bodies contain crystals and that their formation is age dependent. We also demonstrated the crystal structure and chemical composition and the relationship between Gamna-Gandy bodies and chest crises presplenectomy or postsplenectomy.

Evolution of major histocompatibility complex by "en bloc" duplication before mammalian radiation.

Duplications are an important mechanism for the emergence of genetic novelties. Reports on duplicated genes are numerous, and mechanisms for polyploidization or local gene duplication are beginning to be understood. When a local duplication is studied, searches are usually done gene-by-gene, and the size of duplicated segments is not often investigated. Therefore, we do not know if the gene in question has duplicated alone or with other genes, implying that "en bloc" duplications are poorly studied. We propose a method for identification of "en bloc" duplication using mapping, phylogenetic and statistical analyses. We show that two segments present in the major histocompatibility complex (MHC) region of human chromosome 6 have resulted from an "en bloc" duplication that took place between divergence of amniotes and methaterian/eutherian separation. These segments contain members of the same multigenic families, namely olfactory receptors genes, genes encoding proteins containing B30.2 domain, genes encoding proteins containing immunoglobulin V domain and MHC class I genes. We will discuss the fact that olfactory receptors and MHC genes have undergone positive selection, which could have helped in fixation of the surrounding genes.