Syed Wajahat Hussain Wasty ( Ziauddin Medical University )
Khalid Iqbal ( Ziauddin Medical University )
Mirza Rahman Beg ( Aga Khan University Hospital )
Khalid Hussain Mahida ( Ziauddin Medical University )
Ghulam Ali ( Murshid Hospital and Health Care Centre )
Mohammad Tariq ( Murshid Hospital and Health Care Centre )
R.G. aged 14, female of Afghan ethnicity presently settled in the remote areas of Baluchistan, reported with a right sided maxillofacial deformity. She could barely walk because of another deformity that involved the right knee joint (Figures 1 and 2).The two lesions came into observation about nine months back as small swellings and both progressed in dimensions ever since. Maxillary growth extended into the hard palate disfiguring the anatomy of upper denture line from lateral incisor to the last molar. Plain facial radiograph corresponded to the clinical findings. CT scan confirmed that besides maxilla a little portion of the zygoma was implicated, but the orbit was spared by the growth. Biopsy done under local anaesthesia established the histopathology to be compatible with a giant cell tumour. The radiograph of the knee lesion showed involvement of proximal tibia with exuberant callus formation and this lesion was also diagnosed as giant cell tumour on histopathology.
Other investigations showed low haemoglobin (9.0 Gms) with anisocytosis.Serum calcium, uric acid, phosphate, creatinine were within normal parameters. Alkaline phosphatase was 1260mg, (normal 800-1200mg).Serum Parathyroid hormones level was 678pg/ml (normal 7-53pg/ml).Repeat serum calcium showed it to be 7mg. An ultrasound of the parathyroid gland showed a hypo echoic mass measuring 1.8 by 1.1 cms posterior to the lower pole of the left lobe of the thyroid gland. It exhibited vascularity on colour Doppler study and represented a possible parathyroid adenoma. A dual phase Tc-99 Sestamibi parathyroid scan also picked up a focal area of abnormal tracer deposition in the left lower aspect indicative of a probable left lower parathyroid adenoma.
Surgical exploration of the neck identified the enlarged parathyroid gland behind the left lower pole of thyroid. The parathyroid mass was removed in one piece (Figure 3). Histopathology report read "diffuse population of parathyroid tissue mainly composed of the chief cells with sinusoids in between. Focally a nodular pattern with fibro-collagenous trabeculae was identified. The features
Figure 1. Giant Cell involving maxilla.
Figure 2. Giant cell tumour involving tibia.
Figure 3. Parathyroid adenoma- excised specimen.
Figure 4. Facial asthetics- Postoperative.
are compatible with a parathyroid adenoma". Parathyroid hormone levels dropped to 119pg/ml when checked after one week. Serum Calcium levels also registered a drop to 6mgs when parenteral calcium and vitamin D supplements restored it. Alkaline phosphatase was 1190 mg after two weeks.
Two weeks later total maxillectomy was scheduled to relieve the patient off the social embarrassment that she had been facing due to facial deformity. En bloc removal of the lesion was done by a modified Weber-Ferguson incision.The tumour extension involved the greater portion of maxilla including the teeth, some part of zygoma, pterygoid plates, and soft tissue of the overlying cheek. A temporary obturator was fashioned to plug the defect.The histopathology report read" there is abundance of multi-nucleate giant cells with background of uniformly oval mononucleated stromal cells that have indistinct cell membranes. The diagnosis is maxillary giant cell tumour". Her facial aesthetics normalized once the final obturator was fitted (Figure 4).
Two weeks later she suffered a pathological fracture in the lesion on tibia. An orthopaedic assessment was made. It was found that her fracture had healed with a 40% angulation at upper tibial metaphysis.. Anterior wedge osteotomy of the right proximal tibia was done followed by Ilizarov external fixator application. Daily physical therapy and ambulation using parallel bars was started. In the 4 weeks follow-up the patient had satisfactory progress. Her latest serum calcium was 10.9 Gms while the parathyroid hormone has returned to the normal range.
The basic problem of this young girl was primary adenoma of the parathyroid gland. Bony lesions of the maxilla and proximal tibia evolved because of the metabolic disturbance due to inflated parathyroid hormone.
Parathyroid hormone (PTH) acts directly on bone to increase resorbtion and metabolize calcium to increase its circulating levels. PTH depresses phosphate by promoting its excretion in urine. Circulating ionized calcium acts directly on the parathyroid gland as a negative feedback to regulate the secretion of PTH.A hyper parathyroid state (HPTS) is characterized by herpercalcaemic hypophosphatemia, demineralization of bone, hypercalciuria and osteitis fibrosa of the bone marked by marrow fibrosis, bone remodeling with resorption exceeding bone formation.1
Parathyroid adenomas (PA) are almost always solitary. It may lie in close proximity of the thyroid gland or in an ectopic site like mediastinum.The typical PA averages 0.5 to 5 .gms, is a well circumscribed soft nodule, invested by a delicate capsule. In contrast to primary hyperplasia the remaining glands are usually normal in size.2
Giant cell tumour of the bone is a rare primary bone tumour that affect young adults. End of long bones, particularly distal femur and the proximal tibia are preferred locations. Although they are pathologically benign, but clinically behaves aggressively. HPTS promotes giant cell tumour (GCT) formation and its control allows the bone changes to revert.3 In the facial skeleton GCT are frequent in mandible while the maxilla is outstandingly rare.3-5
A usual suspicion index of HPTS is raised serum calcium levels. Paradoxically in this case the calcium levels were rather low. This can be explained possibly as to be due to a transient dissociation between the bone resorption and formation with the raised circulating PTH.Patients with primary hyperparathyroidism may have a decreased suppressibility of PTH secretion. An alternative explanation could be a probable pseudohyperparathyroid state, wherein despite of higher levels of PTH, bone and kidneys show resistance to the action of latter.6 This may result in hypocalcaemia, phosphate retention and low 1,25 dihydroxycholecalciferol levels. Published material from Pakistan showed normal or hypocalcaemic state in primary HPTS questioning the credibility of serum calcium as a screening tool.7
Once the PA or hyperplasia is suspected, localization becomes imperative. Diagnostic tools include ultrasonography, computed tomography, MRI and Technetium 99m Sestamibi scan. Sestamibi scanning has shown greater diagnostic sensitivity and specificity. It is particularly effective when employed as a single modality to localize a PA.8 Frozen sections have been routinely employed during parathyroid surgery. Recently intraoperative rapid parathyroid hormone assays have been employed as an alternative for frozen section for tissue identification. PTH assay is an accurate and time saving diagnostic technique and to date is 100% sensitive and specific for differentiating between parathyroid tumors and thyroid nodules.9
This case merits reporting as the concomitant presentation of giant cell lesions involving maxilla and tibia due to PA is outstandingly rare, to the best of our knowledge and belief.
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4. Vendrel Marques JB, Arkazkoz del Toro JJ, Serra MF, Dana JJ. Brown tumour of maxilla as an initial manifestation of primary hyperparathyroidism, Ann Otorrino Laryngol Ibero Am 1991;18:301-8.
5. Aoine S, Khoctal T, Pahbona C, Turki A, Bakir A. Giant cell lesion of the maxilla disclosing primary hyperparathyroidism,Rev Stoma Maxillofac 2000;101:86-9.
6. Drazner MK. Osteomalacia and rickets. In: Cecil's textbook of medicine. Goldman L, Bennet CJ (eds). 21st ed. Philadelphia: W.B. Saunders, 2001, p. 1395.
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9. Perrier ND, Ituarte P, Kikuchi S, Siperstein AE, Duh QY, et.al. Intraoperative parathyroid aspiration and parathyroid hormone assay as an alternative to frozen section for tissue identification,World J Surg 2000;24:1319-22.