Mixed-sclerosing-bone-dystrophy: report of a case and review of the literature

Melorheostosis and Osteopoikilosis: A Review of Clinical Features and Pathogenesis

Melorheostosis is an exceptionally rare sclerosing hyperostosis that typically affects the appendicular skeleton in a limited segmental fashion. It occasionally occurs on a background of another benign generalised sclerosing bone condition, known as osteopoikilosis caused by germline mutations in LEMD3, encoding the inner nuclear membrane protein MAN1, which modulates TGFβ/bone morphogenetic protein signalling. Recent studies of melorheostosis lesional tissue indicate that most cases arise from somatic MAP2K1 mutations although a small number may arise from other genes in related pathways, such as KRAS. Those cases associated with MAP2K1 mutations are more likely to have the classic "dripping candle wax" appearance on radiographs. The relationship between these somatic mutations and those found in a variety of malignant conditions is discussed. There are also similar germline mutations involved in a group of genetic disorders known as the RASopathies (including Noonan syndrome, Costello syndrome and various cardiofaciocutaneous syndromes), successful treatments for which could be applied to melorheostosis. The diagnosis and management of melorheostosis are discussed; there are 4 distinct radiographic patterns of melorheostosis and substantial overlap with mixed sclerosing bone dysplasia. Medical treatments include bisphosphonates, but definitive guidance on their use is lacking given the small number of patients that have been studied. Surgical intervention may be required for those with large bone growths, nerve entrapments, joint impingement syndromes or major limb deformities. Bone regrowth is uncommon after surgery, but recurrent contractures represent a major issue in those with extensive associated soft tissue involvement.

The concept of type 2 segmental mosaicism, expanding from dermatology to general medicine

In autosomal dominant skin disorders, the well-known type 1 segmental mosaicism reflects heterozygosity for a postzygotic new mutation. By contrast, type 2 segmental mosaicism originates in a heterozygous embryo from an early postzygotic mutational event giving rise to loss of the corresponding wild-type allele, which results in a pronounced segmental involvement being superimposed on the ordinary, non-segmental phenotype. Today, this concept has been proven by molecular analysis in many cutaneous traits. The purpose of this review was to seek publications of cases suggesting an extracutaneous manifestation of type 2 segmental mosaicism. Case reports documenting a pronounced extracutaneous segmental involvement were collected from the literature available in PubMed and from personal communications to the author. Pertinent cases are compared to the description of cutaneous segmental mosaicism of type 1 or type 2 as reported in a given trait. In total, reports suggesting extracutaneous type 2 segmental mosaicism were found in 14 different autosomal dominant skin disorders. In this way, clinical evidence is accumulated that extracutaneous type 2 segmental mosaicism does likewise occur in many autosomal dominant skin disorders. So far, however, molecular proof of this particular form of mosaicism is lacking. The present review may stimulate readers to inform colleagues of other specialties on this new concept, in order to initiate further research in this particular field of knowledge that has important implications for diagnosis, treatment and genetic counselling.

Buschke-Ollendorff syndrome: a novel case series and systematic review

Buschke-Ollendorff syndrome (BOS) is a rare, often benign, autosomal skin disorder. BOS commonly presents with nontender connective tissue naevi and sclerotic bony lesions (osteopoikilosis [OPK]). Herein, we summarize the presenting features of BOS and potential associations by conducting a systematic review of the literature and summarizing a cohort seen at the Hospital for Sick Children (HSC), Toronto, Canada. PubMed was searched using the following terms: 'BOS'; 'dermatofibrosis lenticularis'; 'OPK'; 'LEMD3'; 'elastoma'; 'collagenoma'. Only case reports were included, without date or language restrictions. Cases were further narrowed to those where patients or their families had a combination of skin and bony lesions, or a positive genetic test. Data were summarized using frequencies. In total, 594 reports were discovered, of which 546 (92%) were excluded. The remaining 48 accounted for 164 cases. Skin lesions were noted in 24% of cases and bony lesions in 20%, while 54% of patients had both. In 1% of cases the diagnosis was made on genetic testing alone. A family history was noted in 92% of cases. All patients with spinal stenosis (2%) or shortened status (7%) had OPK. Six per cent of patients had neurological problems. However, 50% of the cohort from HSC had cognitive delays, and only cases from 2007 onwards reported cognitive delays (the prevalence was 17% among those cases). This review confirms the classical diagnostic features of BOS. In addition, it highlights a previously unreported association between a shortened stature and OPK, as well as a possible association with cognitive delays.

Melorheostosis: clinicopathological features, diagnosis, and management

Melorheostosis is a rare sclerosing bone disease. This article describes the histological patterns and radiographic characteristics commonly associated with melorheostosis. A paucity of compiled data about the disease in the literature necessitated a comprehensive review to further define its management.

Melorheostosis may originate as a type 2 segmental manifestation of osteopoikilosis

Melorheostosis is a non-hereditary disorder involving the bones in a segmental pattern, whereas osteopoikilosis is a rather mild disseminated bone disorder inherited as an autosomal dominant trait. Interestingly, melorheostosis and osteopoikilosis may sometimes occur together. In analogy to various autosomal dominant skin disorders for which a type 2 segmental manifestation has been postulated, melorheostosis may be best explained in such cases as a type 2 segmental osteopoikilosis, resulting from early loss of the corresponding wild type allele at the gene locus of this autosomal dominant bone disorder.

Mixed sclerosing bone dysplasia--a case report with literature review

We report a case of mixed sclerosing bone dysplasia in a 26-year-old man. This is a very rare disorder characterized by a variable combination of melorheostosis, osteopoikilosis and osteopathia striata. The disease may be generalized or may show unilateral involvement.

Melorheostosis in a family with autosomal dominant osteopoikilosis

We describe a 19-year-old woman with melorheostosis and osteopoikilosis (mixed sclerosing bone dysplasia). Her sister and mother had osteopoikilosis, but no evidence of melorheostosis. Isolated melorheostosis and melorheostosis with osteopoikilosis are sporadic disorders. Osteopoikilosis is an autosomal dominant trait. Mixed sclerosing bone dysplasia in a family with autosomal dominant osteopoikilosis raises the possibility that the two bone disorders may be related. This family and that of Butkus et al. [1997: Am J Med Genet 72:43-46] suggest that the melorheostosis could be due to a second mutation at the same locus as that which causes autosomal dominant osteopoikilosis.

Mixed sclerosing bone dystrophy. Report of a case and review of the literature

A 63-year old woman was admitted because of hip pain. Radiographs showed multiple round and oval sclerotic lesions involving humeral heads, pelvis, vertebral bodies and both femoral bones. Diaphyseal periosteal proliferation was found in metatarsal bones. A diagnosis of mixed sclerosing bone dystrophy was made. We review clinical, epidemiological and radiological findings of this entity.

Mixed sclerosing bone dystrophy presenting with upper extremity deformities. A case report and review of the literature

We present a detailed study of a 59-year-old white woman with mixed sclerosing bone dystrophy: the rare occurrence of two or more sclerosing bone dysplasias in a single subject. She exhibited features of osteopoikilosis, osteopathia striata and melorheostosis. The symptoms were primarily the result of the melorheostosis lesions which were distributed within the C6 sclerotome. This is an unusual case of mixed sclerosing bone dystrophy in that the upper extremity was the main site of involvement, instead of the usual symmetrical involvement of all limbs. The patient developed a recalcitrant lateral epicondylitis in the un-involved contralateral elbow that required surgical treatment.

Sclerosing bone dysplasias--a target-site approach

Sclerosing bone dysplasias are a poorly understood group of developmental anomalies, much of whose etiology is still obscure. The list of conditions constituting this group is relatively short: osteopetrosis (Albers-Schönberg disease), pycnodysostosis (Maroteaux-Lamy disease), enostosis (bone island), osteopoikilosis, osteopathia striata (Voorhoeve disease), progressive diaphyseal dysplasia (Camurati-Engelmann disease), hereditary multiple diaphyseal sclerosis (Ribbing disease), four types of endosteal hyperostosis (van Buchem disease, Worth disease, Nakamura disease, and Truswell-Hansen disease), dysosteosclerosis, metaphyseal dysplasia (Pyle's disease), craniometaphyseal dysplasia, melorheostosis (Leri disease), and craniodiaphyseal dysplasia. There are instances in which two or more of the above disorders coexist. These are termed "overlap syndromes", most commonly involving osteopathia striata, osteopoikilosis, and melorheostosis. A classification of these dysplasias is elaborated based on a targetsite approach that views them as disturbances in development associated with the processes of either endochondral or intramembranous bone formation, or both. Accumulated evidence suggests that many of these disorders stem from common defects in bone resorption and/or formation during the processes of skeletal maturation and modeling. Finally, the subgroup of overlap syndromes is emphasized as indicating a strong interrelationship between the sclerosing dysplasias of bone, with perhaps a common pathogenesis for many.

Mixed-sclerosing-bone-dystrophy (osteopathia striata and osteopetrosis) and Cushing's syndrome

We present a 33-year-old female patient with the unusual association of mixed sclerosing bone dysplasia and Cushing's syndrome. The patient had the classical features of cortisol overproduction and investigation showed bilateral adrenal adenomas and radiographic abnormalities in bone of osteopathia striata and osteopetrosis: the mixed-sclerosing-bone-dystrophy (MSBD).

Hypophosphataemic rickets and melorheostosis

Hypophosphataemic rickets/osteomalacia has been described in association with fibrous dysplasia and neurofibromatosis. This is the first reported case of melorheostosis associated with hypophosphataemic rickets. The literature is reviewed regarding the known association with the other bone dysplasias.

Intramedullary osteosclerosis. A report of the clinicopathologic features of five cases

The clinicopathologic features of five patients with intramedullary osteosclerosis are presented. The patients, ranging in age from 8 to 52 years (mean 31 years), all presented with pain referred to the lower extremity. The sclerotic lesions involved the entire lower extremity in 1 patient, mid-tibial shaft in 2, distal tibia in 1, and distal fibula in 1 patient. The histopathologic features of intramedullary osteosclerosis overlap with those of melorheostosis. The differential diagnosis also includes a spectrum of entities, each characterized by osteosclerosis and each of which is compared and contrasted to the cases presented.

Osteopathia striata, cranial sclerosis with cleft palate and facial nerve palsy

Osteopathia striata (OS) is a rare bone dysplasia characterized by longitudinal sclerotic striations of the long bones. It is of no clinical importance, but OS associated with cranial sclerosis represents a separate entity with a high incidence of palatine malformations and deafness. Only 19 cases of this entity have been reported in the literature. One patient of this series also had facial nerve paralysis. This paper presents a second case of OS, cranial sclerosis, palatine pathology and recurrent facial nerve paralysis. This incidence of 2/20 (10%) does not seem to be coincidental but raises the possibility that facial nerve palsy is one of the clinical manifestations of this specific bone abnormality.

Mixed sclerosing bone dysplasia coexisting with dysplasia epiphysealis hemimelica (Trevor-Fairbank disease)

The coexistence of mixed sclerosing bone dysplasia and dysplasia epiphysealis hemimelica is a rare anomaly. This combination of abnormalities has not been previously reported. The clinical, radiographic, and pathologic features of this condition are discussed and the methods of treatment of articular complications are reviewed.

Mixed-sclerosing-bone-dystrophy: 42-year follow-up of a case reported as osteopetrosis

We present a detailed metabolic investigation and 42-year radiological follow-up of a 52-year-old man with mixed-sclerosing-bone-dystrophy, the rare occurrence of two or more distinct patterns of sclerosing-bone-dysplasia (e.g., osteopathia striata, osteopoikilosis, melorheostosis) in a single subject. Review of radiographs from 1942, when he was reported to have osteopetrosis, demonstrated diffuse osteosclerosis, osteopathia striata, osteopoikilosis, and focal cortical hyperostosis. Forty-two years later, there had been significant progression and evolution of his skeletal disease with the appearance of new areas of osteopathia striata and osteopoikilosis and a generalized increase in skeletal mass as assessed radiographically. Presence of subperiosteal bone apposition on biopsy of the iliac crest together with chronic mild hypocalcemia, secondary hyperparathyroidism, and hypophosphatemia suggested that enhanced bone formation, perhaps with defective skeletal resorption, is a fundamental abnormality which accounts for the increased bone mass of this patient.

Osteopathia striata with cranial sclerosis affecting three family members

Skeletal surveys were performed on a 38-year-old Japanese mother, her son and daughter. The radiographs of both children showed characteristic features of osteopathia striata. However, in the mother, the skull, mandible, and lower extremities were homogeneously sclerotic with no evidence of a striated pattern of sclerosis in her skeleton. Additional features of striated sclerosis of the mandible in patients with osteopathia striata are discussed.

Vascular anomalies in association with osteodystrophies--a spectrum

A wide spectrum of osseous abnormalities has been reported in association with vascular lesions. Enchondromas, bone hypertrophy, bone lysis, and sclerotic bone lesions have all been reported in association with hemangiomas, lymphangiomas, varicosities, and arteriovenous fistulae. These associations can be grouped into four major syndromes: Maffucci syndrome, mixed sclerosing bone dystrophy with angiodysplasia, congenital angiectatic hypertrophy (Klippel-Trenaunay-Weber syndrome), and massive osteolysis (Gorham syndrome).