Van Buchem disease

Clinical History

A 46-year-old female patient with cervical pain, cephalea, hypoacusis and decrease in visual acuity.

Imaging Findings

A 46-year-old female patient came to our attention with cervical pain, hypoacusis, cephalea and decrease in visual acuity. Cervical spine RX was performed, showing gross thickening of the calvarium, particularly in the frontal and basi-occipital regions, bone overgrowth of jaw, hyperostosis of cervical vertebrae (Fig. 1). Skeleton RX demonstrates significant hyperostosis of clavicle and ribs (Fig. 3), cortical thickening of long bones diaphyses with reduction of medullary canal, especially in femur and tibia (Fig. 4). Also the pelvis appears thickened. Bodies of thoracic and lumbar vertebrae are less involved than spinous processes (Fig. 2).
CT confirms frontal and occipital thickening (>3 cm), petrous bone hyperostosis and reduction of internal and external auditory canal (Fig. 5).
Laboratory shows increase in alkaline phosphatase and bone densitometry (BMD) values are significantly elevated (2.050 g/cm³), T-score 11, 8. Laboratory, clinical and radiological features are strongly suggestive of Van Buchem disease.

Discussion

Van Buchem disease (VBD) is a rare autosomal recessive bone pathology, classified as familiar generalised cortical hyperostosis (FGCH) and characterised by cortical endosteal bone tissue overgrowth.
Two forms of FGCH are known.
Type 1 or Van Buchem disease, with autosomal recessive transmission. Bone abnormalities begin in the first decade and are progressive, alkaline phosphatase (ALP) levels are elevated.
Type 2 or Worth disease, with autosomal dominant transmission. In this pathology the bone overgrowth stops in second decade with normal ALP value [6].
Pathogenesis is related to increase in osteoblasts activity. VBD is determined by deletion in non-coding sequence of SOST gene. The SOST gene, localised in chromosome 17q12-q21, encode sclerostin, which inhibit bone growth. In VBD this protein is absent or significantly low [3-4; 7-8].
Many bones are affected by Hyperostosis: jaws and skull in first, ribs, clavicle and long bones diaphysis. Bodies of vertebras are normal, posterior arches are involved instead. Anomalies are symmetric, progressive determining skeleton overweight up to three times.
Diagnosis is based on familiar anamnesis and radiological features; laboratory reveals ALP high values. Histology shows normal bone structure.
RX shows thickening of the calvarium, particularly in the frontal and basi-occipital regions. Skull base and petrous bones are also involved, sometimes paranasal sinus obliteration is observed. Jaw is a typical localisation, with increase of sagittal and transverse diameters, condyles thickening and open gonial angle [1-2]. Long bones show cortical hyperostosis of the dyaphyses and medullary canal reduction. Hand and feet bones are thickened also at epiphyses. Ribs and clavicle presents significant hyperostosis, cervical column results more involved than dorsal and lumbar column. Pelvis is less hyperostotic than other regions [9-10].
CT confirms RX evidences and is useful in the study of petrous bone, cranial and peripheral nerves foramina.
MR is helpful in evaluation of pheriperal nerves pathology.
Neurological issues are frequent in VBD as nerve encroachment, paralysis of peripheal nerves (V, VII, VIII, X), hypoacusis and hearing loss by sclerosis of ossicular chain and pyramidal region of petrous bone, optic atrophy by stricture of optic foramen. Intracranial hypertension symptoms, cognitive and motor deficit are less common. No case of bone fractures are reported [1-2; 9-10].
Differential diagnosis is between Albers-Schönberg disease, in which skull and jaw are not typically involved, vertebrae are hyperostotic, incidence of fractures is elevated [2], and Engelmann-Camurati disease, characterised by skull, long bones and pelvis cortical thickening (jaw is not affected), pain at extremities, muscular fatigue and typical waddling gait [5].

Differential Diagnosis List

Final Diagnosis

Van Buchem disease

URL:	https://www.eurorad.org/case/9684
DOI:	10.1594/EURORAD/CASE.9684
ISSN:	1563-4086