Lipomas are the most common soft tissue tumors in man. Non-random chromosomal rearrangements have been demonstrated in a high proportion of these benign tumors. Lipomatous tumors are known to occur in a relatively high proportion of patients with MEN 1. We report on a chromosome study of a subcutaneous lipoma, developed by a girl 14 year-old with a history of MEN 1 (stunted growth, bilateral hemianopsia, primary hyperparathyroidism and prolactin-secreting macro pituitary adenoma), localized to the internal surface of the right thigh. Mutation screening of MEN 1 gene (exons 2-10) by DGGE and direct sequencing didn't evidence sequence alteration. However, involvement of the gene can not yet be ruled out. The lipoma (3x1.3 cm) in a short time increased its dimension and another one was detected in abdomen. At the histopathological analysis it was defined as spindle cell lipoma. Cytogenetic analysis performed on direct and short-term cultures revealed a 46,XX,t(3;11)(p21;q13) karyotype in all the metaphases analyzed. Involvement of the 11q13 band in chromosomal rearrangements associated with lipoma has been rarely observed and no lipomas have been described where the 3p21 band, partner of the observed apparently balanced reciprocal translocation, is affected. Findings on mutations of the menin gene in a few MEN 1-assoiated lipomas and loss of heterozygosity at 11q13 in sporadic lipomas have stimulated the hypothesis that lipomas may belong to the group of tumors caused by defects of the MEN 1 gene. Given that controversial evidence has been so far provided on the involvement of the menin gene in lipoma formation in the context of MEN 1 syndrome, we aim at investigating whether or not this gene is disrupted by the 11q13 breakpoint observed in our patient. FISH characterization of the genomic regions involved in the chromosome breakage using BAC probes is in progress to precisely map the breakpoints and search for candidate genes involved in the pathogenesis of lipoma.
"Balanced translocation" T(3;11)(P21;Q13) in a lipoma from a girl with suspected MEN 1 Syndrome / Predieri, Barbara; Iughetti, Lorenzo; M., Losa; L., Larizza; O., Rodeschini; D., Giardino; E., Valtorta; P., Finelli; S., Bernasconi. - In: HORMONE RESEARCH. - ISSN 0301-0163. - STAMPA. - 60 (S2):(2003), pp. 64-65. ((Intervento presentato al convegno 42th Meeting European Society of Pediatric Endocrinology tenutosi a Lubiana nel 25-28 settembre 2003.