Management of Calcaneal Cysts in the Pediatric Population: A Review.

Cysts of the bone are a common pathology that, although benign, are frequently treated because of their tendency to compromise the integrity of affected bone. Two common entities are unicameral bone cysts and aneurysmal bone cysts. Although these are two distinct pathologies, they are treated similarly and thus will be discussed in tandem. The optimal treatment of calcaneal bone cysts in pediatric patients has long been debated among orthopaedic surgeons because of the relatively small number of cases and varied results within the literature. Currently, there are three lines of thought regarding treatment: observation, injection, and surgical intervention. When considering which course of treatment is best for an individual patient, the surgeon must consider the fracture risk without treatment, the risk of complications with treatment, and the recurrence rate with each treatment approach. There are limited data on pediatric calcaneal cysts specifically. Still, there are much data concerning simple bone cysts of long bones in the pediatric population and calcaneal cysts in the adult population. Because of the lack of literature on the subject, there is a need for a review of the available literature and a consensus on the approach to treating calcaneal cysts in the pediatric population.

[Chronic digital wound: epidermoid cyst, osteomyelitis or both? Presentation of two clinical cases and review of the literature]. / Herida crónica digital: ¿quiste epidermoide, osteomielitis o ambos? Presentación de dos casos clínicos y revisión de la literatura.

INTRODUCTION: when faced with a chronic digital injury, the differential diagnosis between osteomyelitis or primary tumor is raised. Coexistence between osteomyelitis and epidermoid bone cyst is not uncommon. MATERIAL AND METHODS: in this article, we describe two cases of epidermoid cysts in distal phalanx of the hand associated with osteomyelitis and a review of the literature is presented. RESULTS: both osteomyelitis and epidermoid bone cyst have been related to the presence of previous trauma at the site of the lesion, nail alterations and chronic phlogotic signs, so it is important to reach a diagnosis of certainty through an anatomopathological study and to perform a good surgical debridement to ensure the healing of both entities. CONCLUSIONS: surgical debridement associated with curettage and filling of the bone defect with bone substitute with antibiotic is a good therapeutic option in the treatment of these lesions.

INTRODUCCIÓN: ante una herida crónica a nivel digital se plantea el diagnóstico diferencial entre osteomielitis o tumor primario. No es infrecuente la coexistencia entre osteomielitis y quiste óseo epidermoide. MATERIAL Y MÉTODOS: en este artículo describimos dos casos de quistes epidermoides en falange distal de la mano asociados a osteomielitis y se presenta una revisión de la literatura. RESULTADOS: tanto la osteomielitis como el quiste óseo epidermoide se han relacionado con la presencia de un traumatismo previo en el sitio de la lesión, alteraciones ungueales y signos flogóticos crónicos, por lo que es importante llegar a un diagnóstico certero mediante un estudio anatomopatológico y realizar un buen desbridamiento quirúrgico que asegure la curación de ambas entidades. CONCLUSIONES: el desbridamiento quirúrgico asociado a curetaje y relleno del defecto óseo con sustituto óseo por medio de antibiótico es una buena opción terapéutica en el tratamiento de estas lesiones.

Outcomes in Unicameral Bone Cyst Management Utilizing a Decision Tree Algorithm Approach.

OBJECTIVE: To determine if utilization of a decision tree algorithm could improve the healing rate of unicameral bone cysts (UBCs). METHODS: Creation of the decision tree algorithm was based on previous literature and assessment of our clinical practice. Demographic, treatment, and radiographic data were collected retrospectively. Radiographic healing was determined using the Neer classification. Healing rate, as well as clinical/radiographic characteristics, were compared based on adherence to the treatment algorithm. RESULTS: Forty-seven subjects were included. Mean age at initial surgery was 10.0 ± 3.3 years in children following the algorithm and 9.1 ± 3.2 years in those deviating from the algorithm (p = 0.393). Follow-up was found to be similar among those following the algorithm (37.5 ± 15.8 months) and those deviating from the algorithm (45.2 ± 24.6 months), p = 0.38. Children who followed the algorithm healed at a rate of 75%, while children who deviated from the algorithm healed at a rate 67% (p = 0.552). CONCLUSIONS: Although we reject our hypothesis that a decision tree algorithm for the management of UBCs in the pediatric population could improve the healing rate, we believe that we uncovered some utility in applying an algorithm to this pathology. Our algorithm was designed to minimize risk to the child and maximize healing with the least number of surgical events. Treating surgeons should consider this proposed pathway to determine the best treatment and to help families understand that these lesions rarely heal with a single-event surgery.

Solitary bone cyst of a lumbar vertebra treated with percutaneous steroid injection: a case report and review of literature.

PURPOSE: We describe a rare case of solitary bone cyst involving the vertebral body of L4. INTRODUCTION: To the best of the authors' knowledge, only 15 cases of solitary bone cysts involving the spine have been reported previously. All the reported cases were treated surgically, including resection and curettage with or without bone grafting. In the current case, treatment was with steroid injection alone. METHOD: A cystic lesion involving the vertebral body of L4 was identified in a 16-year-old girl with persistent low back pain of 2 years' duration. According to the radiological characteristics of the lesion, a diagnosis of solitary bone cyst was suspected. The patient underwent surgical intervention with percutaneous steroid injection alone since there was no evidence of thinned cortex or pathological fracture. The patient was discharged 2 days after this intervention with resolution of the low back pain. RESULT: At the final follow-up 7 months after treatment, the patient was asymptomatic and the beginning of bony healing was evident. CONCLUSION: Herein, we reported an extremely rare case of solitary bone cyst involving the body of the fourth lumbar vertebra. Local steroid injection should be considered as a minimally invasive intervention for a solitary bone cyst involving the spinal column with no evidence of thinned cortex or pathological fracture.

Treatment options of simple bone cysts: the role of bone substitutes, growth factors and literature review.

The solitary bone cyst is a typical tumor-like lesion of the immature skeleton, whose etio-pathogenesis is still unclear. The purpose of this work is to perform a review of the literature about the different surgical approaches focusing on the role of bone substitutes and growth factors. Literature analysis shows injection techniques of substances such as methylprednisolone, autologous bone marrow, demineralized bone matrix, calcium sulphate and surgical techniques that involve the resection and curettage associated with bone graft and/or intramedullary nailing. Although there are good results currently associated to these techniques and the different ways of treatment, the only evidence-based treatment is given by injections of steroids. However, given the high rate of failure, autologous bone marrow and platelet gel represent a viable therapeutic option.

Etiological aspects of solitary bone cysts: comments regarding the presence of the disease in two brothers. Is the genetic theory sustainable or is it pure coincidence? - Case report.

Beginning the study of benign tumors of the bone in children and adolescents, a group of diseases that have in common the clinical aspects, evolution, and surgical treatment, genetic theory in the etiology of the solitary bone cyst, can be sustained by some cases of siblings with the same disease. This paper presents the particular case of two brothers, treated in our clinic for the same condition: solitary bone cyst of the proximal humerus. The two brothers were admitted with the same symptoms, the localization was the same. Because of the genetic studies regarding this condition, we think that it is an interesting aspect of this pathology. This study also tried to find the most appropriate approach in the treatment of these tumors.

Effects of a synovial flap and gelatin/ß-tricalcium phosphate sponges loaded with mesenchymal stem cells, bone morphogenetic protein-2, and platelet rich plasma on equine osteochondral defects.

This study aimed to evaluate the efficacy of a synovial flap and gelatin/ß-tricalcium phosphate (GT) sponge loaded with mesenchymal stem cells (MSCs), bone morphogenetic protein-2 (BMP-2), and platelet rich plasma (PRP) for repairing of osteochondral defects in horses. Osteochondral defects were created on the medial condyle of both femurs (n=5). In the test group, a GT sponge loaded with MSCs, BMP-2, and PRP (GT/MSCs/BMP-2/PRP) was inserted into the defect and then covered with a synovial flap. In the control group, the defect was treated only with the GT/MSCs/BMP-2/PRP. The test group showed significantly higher macroscopic scores than the control group. In addition, hyaline cartilaginous tissue was detected in the test group in areas larger than those in the control group. This study demonstrated that the combination of a synovial flap and GT sponge loaded with MSCs, BMP-2, and PRP promoted osteochondral regeneration in an equine model.

Development and reliability of a multi-modality scoring system for evaluation of disease progression in pre-clinical models of osteoarthritis: celecoxib may possess disease-modifying properties.

OBJECTIVE: We sought to develop a comprehensive scoring system for evaluation of pre-clinical models of osteoarthritis (OA) progression, and use this to evaluate two different classes of drugs for management of OA. METHODS: Post-traumatic OA (PTOA) was surgically induced in skeletally mature rats. Rats were randomly divided in three groups receiving either glucosamine (high dose of 192 mg/kg) or celecoxib (clinical dose) or no treatment. Disease progression was monitored utilizing micro-magnetic resonance imaging (MRI), micro-computed tomography (CT) and histology. Pertinent features such as osteophytes, subchondral sclerosis, joint effusion, bone marrow lesion (BML), cysts, loose bodies and cartilage abnormalities were included in designing a sensitive multi-modality based scoring system, termed the rat arthritis knee scoring system (RAKSS). RESULTS: Overall, an inter-observer correlation coefficient (ICC) of greater than 0.750 was achieved for each scored feature. None of the treatments prevented cartilage loss, synovitis, joint effusion, or sclerosis. However, celecoxib significantly reduced osteophyte development compared to placebo. Although signs of inflammation such as synovitis and joint effusion were readily identified at 4 weeks post-operation, we did not detect any BML. CONCLUSION: We report the development of a sensitive and reliable multi-modality scoring system, the RAKSS, for evaluation of OA severity in pre-clinical animal models. Using this scoring system, we found that celecoxib prevented enlargement of osteophytes in this animal model of PTOA, and thus it may be useful in preventing OA progression. However, it did not show any chondroprotective effect using the recommended dose. In contrast, high dose glucosamine had no measurable effects.

Interventions for treating simple bone cysts in the long bones of children.

BACKGROUND: Simple bone cysts, also known as a unicameral bone cysts or solitary bone cysts, are the most common type of benign bone lesion in growing children. Cysts may lead to repeated pathological fracture (fracture that occurs in an area of bone weakened by a disease process). Occasionally, these fractures may result in symptomatic malunion. The main goals of treatment are to decrease the risk of pathological fracture, enhance cyst healing and resolve pain. Despite the numerous treatment methods that have been used for simple bone cysts in long bones of children, there is no consensus on the best procedure. OBJECTIVES: To assess the effects (benefits and harms) of interventions for treating simple bone cysts in the long bones of children, including adolescents.We intended the following main comparisons: invasive (e.g. injections, curettage, surgical fixation) versus non-invasive interventions (e.g. observation, plaster cast, restricted activity); different categories of invasive interventions (i.e. injections, curettage, drilling holes and decompression, surgical fixation and continued decompression); different variations of each category of invasive intervention (e.g. different injection substances: autologous bone marrow versus steroid). SEARCH METHODS: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (December 2013), the Cochrane Central Register of Controlled Trials (CENTRAL, 2013 Issue 12), MEDLINE (1946 to 12 December 2013), EMBASE (1974 to 12 December 2013) and the China National Knowledge Infrastructure Platform (31 December 2013). We also searched trial registers, conference proceedings and reference lists. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials evaluating methods for treating simple bone cysts in the long bones of children. DATA COLLECTION AND ANALYSIS: Two review authors independently screened search results and performed study selection. We resolved differences in opinion between review authors by discussion and by consulting a third review author. Two review authors independently assessed risk of bias and data extraction. We summarised data using risk ratios (RRs) or mean differences (MDs), as appropriate, and 95% confidence intervals (CIs). We used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system to assess the overall quality of the evidence. MAIN RESULTS: The only included trial was a multicentre randomised controlled trial (RCT) conducted at 24 locations in North America and India that compared bone marrow injection with steroid (methylprednisolone acetate) injection for treating simple bone cysts. Up to three injections were planned for participants in each group. The trial involved 90 children (mean age 9.5 years) and presented results for 77 children at two-year follow-up. Although the trial had secure allocation concealment, it was at high risk of performance bias and from major imbalances in baseline characteristics. Reflecting these study limitations, we downgraded the quality of evidence by two levels to 'low' for most outcomes, meaning that we are unsure about the estimates of effect. For outcomes where there was serious imprecision, we downgraded the quality of evidence by a further level to 'very low'.The trial provided very low quality evidence that fewer children in the bone marrow injection group had radiographically assessed healing of bone cysts at two years than in the steroid injection group (9/39 versus 16/38; RR 0.55 favouring steroid injection, 95% CI 0.28 to 1.09). However, the result was uncertain and may be compatible with no difference or small benefit favouring bone marrow injection. Based on an illustrative success rate of 421 children with healed bone cysts per 1000 children treated with steroid injections, this equates to 189 fewer (95% CI 303 fewer to 38 more) children with healed bone cysts per 1000 children treated with bone marrow injections. There was low quality evidence of a lack of difference between the two interventions at two years in functional outcome, based on the Activity Scale for Kids function score (0 to 100; higher scores equate to better outcome: MD -0.90; 95% CI -4.26 to 2.46) or in pain assessed using the Oucher pain score. There was very low quality evidence of a lack of differences between the two interventions for adverse events: subsequent pathological fracture (9/39 versus 11/38; RR 0.80, 95% CI 0.37 to 1.70) or superficial infection (two cases in the bone marrow group). Recurrence of bone cyst, unacceptable malunion, return to normal activities, and participant satisfaction were not reported. AUTHORS' CONCLUSIONS: The available evidence is insufficient to determine the relative effects of bone marrow versus steroid injections, although the bone marrow injections are more invasive. Noteably, the rate of radiographically assessed healing of the bone cyst at two years was well under 50% for both interventions. Overall, there is a lack of evidence to determine the best method for treating simple bone cysts in the long bones of children. Further RCTs of sufficient size and quality are needed to guide clinical practice.

Steroid injections in the treatment of humeral unicameral bone cysts: long-term follow-up and review of the literature.

BACKGROUND: Retrospective evaluation of long-term effectiveness of the steroid injections treatment in patients with unicameral bone cysts (UBC). METHODS: From January 1993 to April 2005, 23 children affected by proximal humeral UBC were evaluated according to the Neer-Cole classification system and treated with serial methylprednisolone acetate's injections. The patients were followed up at 1, 3, 6 and 12 months and then every year until the adolescence. RESULTS: After treatment, in 15 out of 23 patients (65.2%), the humeral cysts were referred, respectively, as Grade 1 and in four as Grade 2. In 4 patients, a refracture occurred. Statistical analysis showed an overall good response in 82.6% of patients at the end of the follow-up. Minor complication including skin discoloration accounted for 13.04%. CONCLUSIONS: The steroid injections showed to be an alternative excellent treatment for UBC, with complete healing of the lesions in the majority of cases. This procedure is not expensive, mini-invasive, with low surgical risk and short hospitalization.

Cystic bone angiomatosis: a case report treated with aminobisphosphonates and review of the literature.

Cystic angiomatosis (CA) is a rare disease characterized by multifocal hemangiomatous and/or lymphangiomatous lesions of the skeleton with possible visceral organ involvement. The exact pathogenetic mechanism of the disease is still unknown. We describe a patient affected by CA of bone treated with surgical procedures and subsequently with intravenous aminobisphosphonates for 7 years. During the follow-up progression of lesions, the painful symptoms, markers of bone turnover, computed tomographic examination, and bone mineral density were evaluated. Aminobisphosphonate therapy showed an immediate effectiveness in reducing bone pain, with a significant decrease in circulating bone alkaline phosphatase and stable radiological findings during clinical follow-up. In addition, at baseline, high levels of bone biomarkers and cytokines (osteoprotegerin, osteopontin, and interleukin-6) capable of controlling bone metabolism and angiomatosis were identified. Aminobisphosphonate treatment produced a decrease of all these increased markers. Local cell therapy with bone marrow osteoblast precursors did not produce any measurable clinical improvement. Aminobisphosphonate therapy represents an elective treatment for bone angiomatosis syndromes, but further studies are necessary to understand the molecular basis of these disorders and of their pharmacological treatment.

Factors predictive of positive response to steroid therapy in simple bone cysts: an old trick that still works.

PURPOSE: The aim of the study was to identify clinical, demographic and radiological factors predicting a positive response to steroid treatment in simple bone cysts (SBCs). METHODS: A retrospective study was conducted on 62 patients. The mean follow-up period was 9.2 years after the final steroid injection. Recurrences were defined according to Neer's scale as modified by Chang et al.. To identify predictive factors, the group of patients who positively responded to treatment (Neer stages I and II, n = 39, 62.9 %, group 1) were compared with the group in which recurrences occurred (Nerr stages III and IV, n = 23, 37.1 %, group 2). RESULTS: Recurrences were experienced by 37.1 % of the patients (n = 23). Cyst location, numbers of cavities (uni- or multilocular), the area of the cyst and its Enneking stage differed significantly between the groups (p < 0.05). CONCLUSIONS: Steroid therapy may be of benefit in patients with unilocular, small-sized, humeral cysts, classified as Enneking stage IA.

Clinical evaluation of ß-TCP in the treatment of lacunar bone defects: a prospective, randomized controlled study.

The aim of this study was to investigate the potential wide application of beta tricalcium phosphate (ß-TCP) only for bone defects as compared to allograft. 95 patients with a solitary bone cyst were randomly assigned to the treatment. A new radiographic scoring system was employed to calculate the biodegradation of bone graft and to evaluate the influence of multiple factors. At an average of 28.43 months after surgery, a radiographic semi-quantitative analysis revealed that the degradation rates of ß-TCP and the allograft were comparable (p>0.05). Age, complication, packing methods and granule diameters have a significant influence on ß-TCP degradation. The loose packing method and 3-5mm granule size should be employed in clinical practice. A histological analysis of biopsy showed that ß-TCP supported the growth of fibrous tissue, vascular tissue, as well as bone tissue into the implants. The results proved that single ß-TCP is an advantageous alternative to allografts for lacunar bone defect repair and would well guide the design and clinical application of the ß-TCP.

Treatment of symptomatic para-articular intraosseous cysts by percutaneous injection of bone cement.

PURPOSE: To describe the technique and clinical outcome of percutaneous injection of bone cement in the treatment of symptomatic para-articular intraosseous cysts. MATERIALS AND METHODS: Five patients (three men, two women; mean age 35 years) with painful para-articular intraosseous cysts were treated by percutaneous injection of bone cement under combined fluoroscopic and computed tomography (CT) guidance. The lesions were all located in weight-bearing bones, involving the acetabulum, proximal tibia, distal tibia, talus, and calcaneus, respectively. RESULTS: The average amount of bone cement injected was 2.1 ml (range, 0.6-3.5 ml). Calcium phosphate cement was used in four cases and acrylic cement in one case. There were no immediate or delayed complications. Full pain relief was obtained between 1 and 4 weeks after treatment. All patients made a complete recovery and were pain-free at their last visit. CONCLUSIONS: Percutaneous injection of bone cement was a safe and efficient technique in the management of symptomatic para-articular intraosseous cysts in our population.

Unicameral bone cyst: radiographic assessment of venous outflow by cystography as a prognostic index.

The aim of this study was to determine the benefits of cystography in the management of a simple bone cyst, its implication in the final result of the treatment after corticoid intracystic injections, and the presence of secondary effects. We retrospectively reviewed 42 patients diagnosed with a simple bone cyst. Cystography was performed before the corticoid injection. The presence or absence of loculation intracyst and the existence and number of venous outflows were determined. According to the venous drainage, cysts were classified as type 0 when a venous outflow did not exist and as type 1 when there was a rapid venous outflow (<3 min). The treatment protocol included a maximum of three corticoid injections at an interval of 6 months. Healing of the cyst was determined on the basis of Neer's criteria. Secondary effects and surgical complications were assessed. Cystography studies showed a unicameral bone cyst with absent loculation in 16 cases (37.3%), whereas the lesion showed multiloculation in 26 cases (62.7%). There was no statistical difference between loculation intracyst (present or absent) and the final outcomes of the 42 cysts treated with a steroid injection (P=0.9). Cystography showed a negative venogram in 10 cases (23.8%), whereas the cysts showed a rapid venous outflow in 32 cases (76.2%). On the basis of Neer's classification, all patients with a negative venogram achieved complete healing of the cyst. Patients with a rapid venous outflow achieved complete healing in 14 cases (Neer I). In two patients, the healing was incomplete at the end of the follow-up period (Neer IV). In most cases (21 cysts), healing was partial (Neer II). Five patients showed a recurrence after initial healing of the cyst (Neer III) (P<0.05). The number or the size of veins did not affect healing of a bone cyst (P=0.6). Two patients with a rapid venous outflow showed a generalized hypertrichosis after the first injection of corticosteroids. Sex and age at the initiation of the first injection were not significant factors of healing (P=0.4). The average follow-up time was 59 months (24-60 months). Cystography provides morphological and functional information of simple bone cyst. It is a useful test before the administration of percutaneous injections of sclerosing substances. It facilitates the differentiation of cysts that may achieve complete healing (negative venogram) from those that tend to show recurrence (rapid venous outflow). Therapeutic material should be introduced slowly and a second trocar should always be placed to decrease the risk of migration in cysts with communication with the venous system.

The modern treatment of the simple bone cysts.

This study was performed between 2007-2012 and encompasses 94 patients. The patients were divided in two groups. The first group included the patients who have benefited from surgical treatment (42 cases) and the second one included patients who benefited from conservative treatment. Out of the total number of cases, 63 cases showed an intact simple bone cyst that was most of the time an accidental discovery. 31 patients presented with fracture sustained on a simple bone cyst. There were 63 boys and 31 girls. Their mean age was 9.9 +/- 2.34 years. Single injection was performed for 49 patients; the rest had double or triple injections. The mean follow-up was 34.5 +/- 6.6 months. The procedure succeeded in obtaining healing in 77 cysts (82%). Cyst index of more than five and cortical index of less than 1 mm were significantly prone to pathological fractures and had significant poor results after treatment. Our results suggested that an autogenous bone marrow injection is a safe and effective treatment method for simple bone cysts, when compared with the surgical management, but sometimes-repeated injections are necessary. Cyst index and cortical width are good indicators for treatment outcome.

Mid- and long-term clinical results of surgical therapy in unicameral bone cysts.

BACKGROUND: Unicameral (or simple) bone cysts (UBC) are benign tumours most often located in long bones of children and adolescents. Pathological fractures are common, and due to high recurrence rates, these lesions remain a challenge to treat. Numerous surgical procedures have been proposed, but there is no general consensus of the ideal treatment. The aim of this investigation therefore was to study the long-term outcome after surgical treatment in UBC. METHODS: A retrospective analysis of 46 patients surgically treated for UBC was performed for short and mid-term outcome. Clinical and radiological outcome parameters were studied according to a modified Neer classification system. Long-term clinical information was retrieved via a questionnaire at a minimum follow-up of 10 years after surgery. RESULTS: Forty-six patients (17 female, 29 male) with a mean age of 10.0 ± 4.8 years and with histopathologically confirmed diagnosis of UBC were included. Pathological fractures were observed in 21 cases (46%). All patients underwent surgery for UBC (35 patients underwent curettage and bone grafting as a primary therapy, 4 curettage alone, 3 received corticoid instillation and 4 decompression by cannulated screws). Overall recurrence rate after the first surgical treatment was 39% (18/46), second (17.4% of all patients) and third recurrence (4.3%) were frequently observed and were addressed by revision surgery. Recurrence was significantly higher in young and in male patients as well as in active cysts. After a mean of 52 months, 40 out of 46 cysts were considered healed. Prognosis was significantly better when recurrence was observed later than 30 months after therapy. After a mean follow-up of 15.5 ± 6.2 years, 40 patients acknowledged clinically excellent results, while five reported mild and casual pain. Only one patient reported a mild limitation of range of motion. CONCLUSIONS: Our results suggest satisfactory overall long-term outcome for the surgical treatment of UBC, although short-and mid-term observation show a considerable rate of recurrence independent of the surgical technique.

Multicystic bone disease (Gorham-Stout syndrome) in a spider monkey (Ateles geoffroyi ).

BACKGROUND: In April 2000, a 2.5-year-old pet female Geoffroyi's spider monkey presented for reduced activity, a subdued demeanor, and boney enlargement involving both radii. METHODS: On further examination, polyostotic bone cysts were identified involving many of the tubular bones and were identified radiographically. Microscopic examination of a bone biopsy revealed hemorrhage and other characteristics typical of an aneurysmal bone cyst. In addition, excessive osteoclasia was noted, in association with fibrotic areas rather than with Howship's lacunae as expected from a growing animal. RESULTS: These findings were consistent with Gorham-Stout syndrome, a rare condition reported previously in ∼175 human cases and in a dog at necropsy. The diet history and further testing suggested a negative calcium balance. Treatment included the administration of bis-phosphonates, which appeared to bring about marked improvement. Almost 8 years later (November 2008), radiographs were again taken and suggested some resolution of bone cysts, primarily those in the legs. CONCLUSIONS: This represents the first reported case and a potential therapy for this rare condition in a non-human primate.