SummaryHereditary multiple exostoses (HME) is an inherited genetic condition characterized by the presence of multiple exostoses (osteochondromas). MHE is a relatively rare autosomal dominant disorder, mainly caused by loss of function mutations in two genes: exostosin-1 (EXT1) and exostosin-2 (EXT2). These genes are linked to heparan sulfate (HS) synthesis, but the specific molecular mechanism leading to the disruption of the cartilage structure and the consequent exostoses formation is still not resolved. The aim of this paper is to encounter the main aspects of HME reviewing the literature, in order to improve clinical features and evolution, and the metabolic-pathogenetic mechanisms underlying. Although MHE may be asymptomatic, a wide spectrum of clinical manifestations is found in paediatric patients with this disorder. Pain is experienced by the majority of patients, even restricted motion of the joint is often encountered. Sometimes exostoses can interfere with normal development of the growth plate, giving rise to limb deformities, low stature and scoliosis. Other many neurovascular and associated disorders can lead to surgery. The most feared complication is the malignant transformation of an existing osteochondroma into a secondary peripheral chondrosarcoma, during adulthood. The therapeutic approach to HME is substantially surgical, whereas the medical one is still at an experimental level. In conclusion, HME is a complex disease where the paediatrician, the geneticist and the orthopaedic surgeon play an interchangeable role in diagnosis, research and therapy. We are waiting for new studies able to explain better the role of HS in signal transduction, because it plays a role in other bone and cartilage diseases (in particular malignant degeneration) as well as in skeletal embryology.

Growth and development were followed in 7 preterm newborn infants who received fluoroquinolones in the neonatal period. Quinolones were used as a "life saving" therapy in cases of sepsis caused by bacterial agents sensitive only to these drugs. Two other groups of neonates matched for gender, birth weight and gestational age served as controls. Although the quinolone group had more severe illness, no statistically significant differences were observed in growth and development between the groups. No osteoarticular problems or joint deformities were observed in the quinolone group. Therefore, quinolones could be a therapeutic option for newborns with sepsis caused by multiply resistant organisms.

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A healthy man in his 20s presented with a several-month history of asymptomatic, slightly erythematous cutaneous nodules, measuring 1.5 to 3.0 cm, over the calcanea (Figure , A). Physical examination revealed violaceous plaques, measuring 2 to 3 cm, on the extensor surface of the knees, bilaterally (Figure, B). Excisional biopsy specimens were obtained (Figure, C and D).Erythematous calcaneal nodules A Violaceous knee plaques B Calcaneal nodule specimen C Plaque specimen D Figure. A, Multiple asymptomatic erythematous nodules measuring 1.5 to 3.0 cm at presentation. B, Multiple violaceous plaques measuring 2 to 3 cm on the extensor surface of the knees. C, Excisional biopsy specimen of a calcaneal nodule (hematoxylin-eosin, original magnification ×20). D, Excisional biopsy specimen of a plaque (hematoxylin-eosin, original magnification ×20). WHAT IS YOUR DIAGNOSIS? A. Elastolytic granuloma B. Knee-located erythema elevatum diutinum (EED) with a calcaneal late-stage nodular component C. Epithelioid sarcoma D. Storiform collagenoma Clinical Review & Education JAMA Dermatology Clinicopathological Challenge