Lower back pain and pain in the left leg in an otherwise fit gentleman. Ten months later he lost 13 kg and had worse pain. MRI revealed widespread metastasis with significant disruption to S1. Investigations revealed primary hyperthyroidism Ultrasound-scan of the neck,T-99m-Sestamibi-scan,skeletal-survey, bone-scan and F-18-FDG-PET scan revealed multiple brown tumours.
This gentleman presented with a two-year history of left sided lower back pain and pain in the left leg. MRI findings were insignificant.He received two sets of facet joint injections and physiotherapy which completely relieved the pain. The pain returned ten months later, emanating from the region of the left sacroiliac joint. He lost 13 kg in weight. The new MRI-scan showed widespread metastasis and cystic changes (see figure 1) with significant invasion of the anterior part of L1 and almost complete obliteration of the left first sacral neural exit foramen which appeared to account for his symptoms. Open biopsy and decompression of the left lumbo-sacral-canal revealed brown tumours secondary to hyperparathyroidism. His corrected serum Calcium, alkaline phosphate, parathyroid hormone (PTH) level and 24hr urinary Ca excretion were raised. An ultrasound-scan of the neck showed a parathyroid adenoma. A technetium-99m-Sestamibi-scan confirmed this with multiple additional areas of increased uptake in the bony skeleton. A skeletal survey and bone scan revealed further brown tumours in the hands, feet, femora and both patellae. A huge parathyroid tumour was excised completely and frozen section showed a parathyroid tumour consistent with an adenoma. Full histological analysis revealed a low grade parathyroid carcinoma. Excision was complete but there was evidence of capsular and vascular invasion. F-18-FDG-PET scan demonstrated multiple metabolically active lesions in the areas of the brown tumours. Post-operative MRI, 5 1/2 months after operation, revealed partial resolution of all the brown tumours both in terms of marrow signal and size (see figure 2)
In 90% of patients with hypercalcaemia the cause will be either hyperparathyroidism or malignancy. These may be distinguished by whether the parathyroid hormone level is elevated or not. Primary hyperparathyroidism affects 1 in 1000 adults in the UK1 and may be present for months or even years before the diagnosis is made, with serum calcium levels usually below 3.0mmol/L. Symptoms are absent or mild at this level. The presentation is frequently more dramatic in malignancy with greater elevation of the serum calcium to 3.5 mmol/L or greater, and more pronounced symptoms. Osteitis fibrosa cystica is an infrequent manifestation of hyperparathyroidism and occurs due to subperiosteal bone resorption. Skeletal changes are now only identified in approximately 5% of patients with hyperparathyroidism. It is unusual in the spine and has not previously been reported to occur at multiple non-contiguous spinal levels. Brown tumours in the spine have been described as causing spinal cord and cauda equina compression. Fortunately this patient did not develop any neurological deficit, despite the volume of tumour in the sacral spinal canal. Surgery is the definitive treatment for primary hyperparathyroidism and is recommended in patients with skeletal or renal complications, or in those who are symptomatic (see table 1, The National Institutes of Health guidelines for parathyroidectomy2). It should aim to remove the abnormal parathyroid gland(s) and, in the spine, decompress and stabilise where necessary. Kashkari et al3 reported that needle aspiration biopsy is a safe and rapid method of diagnosing osteitis fibrosa cystica. Analysis of such specimens is difficult, however, and may well be affected by local pathological knowledge or resources. In our case both the CT guided biopsy and open biopsy provided the same histological result, but the differential diagnosis was not suggested until a musculo-skeletal pathologist saw the second sample. Most reported cases of spinal involvement are in patients with secondary hyperparathyroidism related to chronic renal failure.4,5,6,7,8,9 In this case primary hyperparathyroidism secondary to parathyroid carcinoma presented with multi-level spinal involvement. An excellent result was achieved following parathyroidectomy, with resolution of the spinal disease-inkeeping with previous reports suggesting that cancellous bone makes a prompt recovery, bone mineral density doubling from as early as the end of the first week10. Follow-up 13 months after demonstrated a residual L1 deformity which was stable with no other signs of brown tumours in his spine. The sacral cysts had almost completely resolved. We believe that this is the first presentation of a case of non-contiguous multiple level spinal involvement. The possibility of such "Skip lesions" should be considered when interpreting lesions in the spine caused by a primary pathology elsewhere. It could be due to a cause other than metastasis.
Parathyroid Carcinoma Presenting as Lower Back Pain
Based on the provided MRI images (including sagittal and axial planes) and other relevant examination results, multiple abnormal lesions can be observed in several segments of the lumbar and sacral spine. These lesions appear as cystic or osteolytic changes within multiple vertebral bodies and paravertebral tissues. Notably in the S1 region, the lesion extends extensively with significant local bone destruction involving the spinal canal, leading to a mass effect. In certain segments, reduced bone density or abnormal signals can be seen at the vertebral edges or within the vertebrae, forming irregular cystic or osteolytic lesions. On MRI, the lesions present as low to intermediate signal on T1 and relatively high signal on T2, with heterogeneous enhancement after contrast administration. No remarkable swelling was noted in the adjacent soft tissues, although partial soft tissue involvement is suggested. Overall, the imaging findings are consistent with “multiple osteolytic/cystic changes,” requiring differential diagnosis with metastatic tumors, giant cell tumor of bone, or brown tumors.
The patient’s significant weight loss, worsening pain, and multifocal bone destruction on imaging initially raise concern for metastatic bone lesions. However, in typical cases of multiple bone metastases, laboratory tests or PET-CT often identify a clear primary cancer site or a more characteristic metastatic pattern. In this case, further investigations (including parathyroid function and pathological biopsy) ruled out common primary malignancies.
Multiple myeloma can also present as multifocal bone destruction. However, it is often accompanied by specific laboratory abnormalities such as protein electrophoresis (M protein) and abnormal serum free light chains. In this patient, the focus shifted to hypercalcemia and elevated parathyroid hormone levels, making multiple myeloma less likely.
Giant cell tumors generally affect a single bone segment or the area adjacent to a joint surface, which does not fully match the multiple, non-contiguous osteolytic lesions seen in this case. While giant cells may be present on histology, parathyroid function testing is crucial for definitive diagnosis.
Brown tumors resulting from primary or secondary hyperparathyroidism can manifest as osteoporosis, bone destruction, and cystic degeneration, accompanied by elevated serum calcium and parathyroid hormone levels. In this case, combined with neck ultrasound, parathyroid imaging (e.g., 99mTc-MIBI-SPECT), and pathological biopsy, the findings are highly suggestive of brown tumors.
Taking into account the patient’s clinical features (low back pain, left leg pain, weight loss), laboratory tests (hypercalcemia, significantly elevated parathyroid hormone), and radiologic findings (multisegment osteolytic destruction and cystic lesions), confirmed by dual pathological biopsies, the final diagnosis is:
Primary Hyperparathyroidism (caused by a parathyroid tumor) leading to multiple Brown Tumors (Osteitis Fibrosa Cystica).
Rehabilitation should be carried out step by step after surgical and medical management of the underlying cause, emphasizing safety and individualized treatment:
Frequency, Intensity, Time, and Type (FITT) of exercise should be individualized and progressively adjusted (Progression) under the guidance of orthopedic or rehabilitation professionals. For patients with fragile bones or poor cardiopulmonary function, exercise intensity may need further reduction, and low-impact exercises are recommended to ensure safety.
This report is based on the available medical history and imaging data for reference only. It does not replace formal in-person consultations or other professional medical opinions. Specific treatment plans should still be formulated according to detailed changes in the patient’s condition and further evaluation by specialized physicians.
Parathyroid Carcinoma Presenting as Lower Back Pain
