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Primary pachydermoperiostosis (PDP) is a rare syndrome, characterized by digital clubbing, periostosis, and pachydermia. We have evaluated biochemical bone turnover markers, including components of interleukin-6 (IL-6) and osteoprotegerin/receptor activator of nuclear factor (NF)-kappaB ligand (OPG/RANKL) systems, in an 18-year-old man affected by primary PDP. The acute phase of the disease was characterized in our patient by high serum levels of IL-6 and RANKL. The observed high serum levels of these parameters are associated with increased values in markers of bone resorption (degradation products of C-terminal telopeptides of type-I collagen and urinary hydroxyproline/creatinine ratio) and reduced serum levels of bone alkaline phosphatase, a marker of bone formation. Serum levels of osteotrophic hormones were in the normal range. Our data suggest that, despite the radiographic findings, the acute phase of primary PDP is characterized by increased bone resorption, probably mediated by IL-6 and RANKL. [ABSTRACT FROM AUTHOR]

Competing Interests: Competing interests: None declared.

Giant cell tumor is a rare complication of Paget's disease of bone. Typically, this tumor occurs in the case of polyostotic disease and only in pagetic bones. This tumor rarely has been seen in multiple family members who have Paget's disease, although Paget's bone disease clearly has a hereditary component. Our report documents four cases of polyostotic Paget's bone disease complicated by benign giant cell tumor. In two patients, the giant cell tumor also was multifocal. All patients were from one family. They were born in Avellino and reside in Campania, a Southern Italian region. The ancestors of the patients with familial giant cell tumor in Paget's bone disease were born in the same geographic area. These data suggest that a combination of environmental and genetic factors could be responsible for linkage of the patients born in Avellino with this neoplasm that is highly unusual in patients with Paget's disease of bone.

Objective: Interleukin-6 (IL-6) and its soluble receptor (sIL-6R) stimulate osteoclast formation and activity. The primary cell abnormality in Paget's disease of bone (PDB) involves osteoclasts. Pagetic osteoclasts overproduce IL-6 and IL-6 receptor in vitro. In vivo, IL-6 serum levels are very high in the acute phase of PDB. The aim of this study was to evaluate the modification in the serum levels of IL-6, sIL-6R and osteotropic hormones (parathormone, 25OHD3 and 1,25(OH)2D3) as a in long-term response to clodronate treatment in patients with PDB., Methods: 16 patients (8 females) with polyostotic PDB were studied. IL-6, sIL-6R and osteotropic hormones serum levels were evaluated in active PDB and after clodronate treatment (300 mg injected intravenously for 5 consecutive days). The sequential changes in total alkaline phosphatase (tALP) serum levels were used to assess the maximal pharmacological response to treatment., Results: In untreated pagetic patients, mean serum levels of IL-6 (3.20+/-1.18 pg/ml) and sIL-6R (35.02+/-8.33 ng/ml) were significantly increased. Serum osteotropic hormone levels fell within the normal range. Eight weeks after treatment, the maximal pharmacological response to clodronate was associated with a significant reduction of sIL-6R serum levels in all patients, without a significant variation in serum IL-6 and osteotropic hormone levels. Moreover, we observed a correlation between lower sIL-6R serum levels before clodronate therapy and complete remission of PBD, defined as a decrease of tALP serum levels within the normal range., Conclusion: The decrease in serum sIL-6R levels could be one of the molecular mechanisms that play a role in the clinical response to clodronate treatment in PDB.