Osteoclastomas ('brown tumours') and spinal cord compression: a review.

Brown tumours are an uncommon manifestation of primary and secondary hyperparathyroidism. There are numerous case reports of brown tumours arising in various parts of the skeleton. They can therefore present a wide range of clinical manifestations. A recent case highlighted the need for heightened awareness of the diagnosis and prompted a literature review.

Introduction

Many patients on long-term dialysis develop secondary hyperparathyroidism. Brown tumours, an unusual but recognized complication of both primary and secondary hyperparathyroidism, have been reported to occur in 4.5% of patients with primary and 1.5–1.7% of those with secondary disease [1].

The case

A frail 57-year-old male haemodialysis patient with known severe peripheral vascular disease presented to the vascular surgeons with a 4-week history of worsening leg weakness. A magnetic resonance imaging (MRI) scan of the spine (Figure 1) showed multiple lesions, the largest of which was at T12, causing cord compression. He was subsequently transferred to Oncology and was initiated on steroids and radiotherapy. Subsequently, a bone biopsy was performed. This showed portions of bone containing a cellular spindle cell proliferation with abundant brown, granular and globular material and scattered groups of multinucleate giant cells of the osteoclast type, which, in the context of high parathyroid hormone levels, was diagnosed as a brown tumour of hyperparathyroidism. Despite significant cord compression, our patient did not undergo surgical decompression due to significant comorbidities. He was initially commenced on increased medical therapy for his secondary hyperparathyroidism including cinacalcet. However, after 6 weeks the patient had not responded to treatment, and he therefore underwent a four-gland parathyroidectomy. He regained some but not all muscle power following prolonged physiotherapy.

Fig. 1.

MRI of spine showing the tumour at T12.

Discussion

Brown tumours (or osteoclastomas) are an unusual but recognized complication of both primary and secondary hyperparathyroidism and have been reported to occur in 4.5% of patients with primary and 1.5–1.7% of those with secondary disease [1]. They are composed of multinucleated osteoclasts, stromal cells and matrix [2, 3] and are benign in nature, although they can cause significant morbidity due to secondary effects such as spinal cord compression. The name derives from their vascularity, haemorrhage and consequent haemosiderin deposition, which give these tumours their characteristic colour [2, 3]. Brown tumours are histologically similar to other giant cell tumours and diagnosis therefore depends on the histological findings along with a raised PTH level [1, 4, 5].

In terms of the underlying pathology, brown tumours are a localized form of osteitis fibrosa, the classical histological form of high-turnover renal osteodystrophy. They most commonly arise from the tuberous parts of the jaw, and in long bones and ribs [1]. Spinal cord lesions are less common [5-7] and historically reported more frequently in patients with primary hyperparathyroidism. However, a recent literature review noted increased reporting of vertebral brown tumours in patients with ESRD over the last few decades for which this may simply reflect increased reporting or be a marker of increased survival in dialysis populations resulting in a true increase in the incidence of cases [8].

The first case of brown tumours involving the spine in a haemodialysis patient was reported in 1978 by Ericsson et al. [9]. In total and excluding the case presented here, 36 other cases of spinal cord compression secondary to brown tumours have been reported in the literature (Table 1). Of these, 64% (23 of 36) of cases have been reported in patients with secondary hyperparathyroidism due to chronic kidney disease (CKD). It is more common in females (61.1%). The mean age of the patients with secondary hyperparathyroidism was 43.67 ± 14.9 years. Most of the cases (58.3%) reported involvement of thoracic spine. These are similar findings to those quoted in a recently published review [8]. All cases presented with signs and symptoms of cord compression, 77.8% (28 of 36) had surgical resection of tumour and 69.4% had parathyroidectomy. One case did not report the modality of treatment.

Table 1.

Summary of the spinal brown tumour cases reported in the literature

	Year published	Sex/age (years)	Hyperparathyroidism	Spine involved	Symptoms	Treatment
Shaw and Davies [11]	1968	F/58	Primary	T10 pedicle	Paraparesis and urinary retention	Surgical resection and parathyroidectomy
Shuangshoti et al. [12]	1972	M/32	Primary	L4 posterior elements	Progressive paraparesis and reticular pain	Surgical resection and parathyroidectomy
Sundaram and Scholz [13]	1977	F/63	Primary	T10 body and pedicle	Paraplegia and urinary retention	Surgical resection and parathyroidectomy
Siu et al. [14]	1977	F/64	Primary	T10	Paraplegia, sensory loss, urinary retention	Surgical resection, Parathyroidectomy
Ericsson et al. [9]	1978	F/47	Secondary	Cervico-thoracic	Paresis	Surgical resection and parathyroidectomy
Ganesh et al. [15]	1981	M/40	Primary	T2 body and pedicle	Paraparesis, radicular pain	Parathyroidectomy
Bohlman et al. [7]	1986	F/69	Secondary	Thoracic	Incipient Paraplagia	Steroid therapy
Yokota et al. [16]	1989	F/58	Primary	T5 pedicle	Paraparesis and numbness	Surgical resection and Parathyroidectomy
Pumar et al. [17]	1990	F/24	Secondary	Thoracic	Incipient Paraplagia	Surgical resection
Kashkari et al. [18]	1990	F/51	Primary	T6 and T7 bodies	Paraparesis	Surgical resection and parathyroidectomy
Barlow and Archer [19]	1993	F/31	Secondary	Cervical	Neck pain and cervicobrachial neuralgia	Parathyroidectomy and Minerva jacket
Sarda et al. [20]	1993	F/23	Primary	T3-4	Paraparesis and radicular pain	Surgical resection and parathyroidectomy
Motateanu et al. [21]	1994	M/57	Primary	L4-5 facet	Lower limb radicular symptoms	Surgical resection
Mourelatus et al. [22]	1998	M/48	Secondary	T2 body and posterior elements	Paraparesis and incontinence	Not reported
Fineman et al. [23]	1999	F/37	Secondary	Thoracic	Incipient oaraplagia	Surgical resection and parathyroidectomy
Azria et al. [24]	2000	F/40	Secondary	Thoracic	Back pain	parathyroidectomy
Masutani et al. [25]	2001	F/39	Secondary	Thoracic	Paraplegia	Surgical resection and parathyroidectomy
Paderni et al. [26]	2003	F/45	Secondary	L2-L3,L5,S1	Paraparesis	Surgical resection and parathyroidectomy
Mustonen et al. [27]	2004	M/28	Primary	L2	Lower limb radicular pain and numbness	Parathyroidectomy
Vandenbussche et al. [5]	2004	F/34	secondary	Thoracic	Spinal cord compression	Decompression and parathyroidectomy
Tarass et al. [6]	2006	M/42	secondary	Sacral	Cauda equina syndrome	Surgical decompression and parathyroidectomy
Haddad et al. [28]	2007	F/62	Primary	T2-4	Paraparesis	Surgical resection and parathyroidectomy
Kaya et al. [29]	2007	M/72	Secondary	T1 body and transverese process	Unilateral arm pain and paresis	Radical excision
Khalil et al. [30]	2007	M/69	Primary	L2 body and pedicle	Lower limb radicular pain	Surgical resection
Wiebe et al. [3]	2008	F/33	Secondary	Thoracic	Paraparesis	Surgical decompression and parathyroidectomy
Hoshi et al. [31]	2008	F/23	Primary	Sacrum	Lower limb radicular pain	Parathyroidectomy
Ren et al. [32]	2008	M/47	Secondary	T4 body and pedicle	Paraparesis and numbness	Surgical resection
Mak et al. [4]	2009	F/65	Yes	Thoracic	Back pain and paraplegia	Surgical decompression
Pavlovic et al. [33]	2009	M/40	Secondary	T9 body and pedicle	Paraplegia	Biopsy and surgical resection
Noman Zaheer et al. [34]	2009	M/30	Secondary	Thoracic	Back pain and minimal neurological problem	Surgical resection
Kampschreur et al. [35]	2010	M/43	Secondary	Thoracic	Upper abdominal pain radiating to back	Surgical resection and subtotal parathyroidectomy
Gheith et al. [36]	2010	M/19	Secondary	Lumbar	Back pain and paraparesis	Surgical decompression and parathyroidectomy
		F/25	Secondary	Cervical	Neck pain and paraparesis	Surgical decompression and parathyroidectomy
Mateo et al. [37]	2011	F/34	Secondary	C2	Neck pain	Biopsy and parathyroidectomy
Fargen et al. [8]	2011	F/33	Secondary	L1	Paraparesis	Laminectomy and bracing
Araujo et al. [38]	2012	M/47	Secondary	Lumboscral	Back pain and difficulty in gait	Posterior laminectomy and tumour excision

Vertebral brown tumours can either present acutely due to cord compression with progressive neurological deficit or with symptoms caused by vertebral fracture [1, 4]. Radiological findings depend on the modality used. On plain X-rays, brown tumours usually present as an osteolytic lesion [1, 10]. In the long bones, these are usually well demarcated but in the spine the margins can be difficult to see. A computed tomography scan can confirm an osteolytic lesion with no cortical disruption or periosteal reaction [1, 5] but an MRI scan will provide a far more detailed image and often demonstrates the fluid cysts which are a highly suggestive marker of a brown tumour [5]. Brown tumours may mimic metastases on bone scan due to the presence of ‘hot spots’, a result of intense osteoclastic activity [8].

Treatment of brown tumours centres around treatment of the secondary hyperparathyroidism. Medical treatment includes aggressive dialysis, treatment with phosphate binders, vitamin D supplements and cinacalcet, although previous case reports have questioned the effectiveness of the latter [3, 8]. Parathyroidectomy is also commonly performed but requires a patient to be fit enough for a general anaesthetic. Normalizing bone biochemistry and parathyroid hormone levels generally result in bone remineralization and resolution of the tumours. However, remineralization may not happen in a spinal lesion; this is presumed to be due to the reduced amount of mechanical stress in comparison to long bones [6].

In conclusion, the possibility of a brown tumour should form part of the differential diagnosis in patients with advanced kidney disease presenting with peripheral neurological symptoms and a mass lesion. This case demonstrates the need for a high index of suspicion and highlights the need for nephrologists to be involved in the ongoing care of dialysis patients admitted to other specialties.

Conflict of interest statement

None declared.