JRSM >
Volume 96, Number 8 >
Pp. 404-406
Charing Cross Hospital, Fulham Palace Rd, London W6 8RF
1 Section of Cellular Pathology, Department of Pathology, Mayday University
Hospital, Croydon CR7 7YE, UK
Correspondence to: Dr A Stewart E-mail: astewart{at}hhnt.org
Lymphadenopathy after tumour resection is an important indicator of recurrence, but other explanations must be excluded.
CASE HISTORY
The patient was a man of 46 who in 1995 had sustained a fracture of the right medial femoral condyle apparently due to an aneurysmal bone cyst. He was treated with open reduction and internal fixation with a bone graft. The knee became increasingly painful and swollen, and in March 1997 X-rays showed a destructive tumour involving the whole of the lower end of the femur with extension into the soft tissue medially and posteriorly. The patient was keen to avoid amputation, so a rotating-hinge knee replacement was custom built for him with cobalt, chromium and molybdenum and with ultra-high-molecular-weight polyethylene on the articulating surfaces. At operation, the distal end of the femur was excised along with all visible tumour, although there was some spillage of tumour contents. Histological specimens showed an osteoclastoma consisting of spindle cells with minimal nuclear pleomorphism and some mitoses. There was no evidence of vascular invasion and the excision seemed complete. He had radical radiotherapy to his right knee postoperatively.
At routine follow-up in November 2000 there was a palpable mass in the right groin which ultrasonography showed to be a cluster of enlarged lymph nodes. The mass did not decrease in size with antibiotic treatment. Subsequent CT showed enlargement of superficial inguinal and external iliac lymph nodes on the right, the biggest being 2.5 cm in diameter. There was a 1 cm lymph node in the right side of the pelvis immediately posterior to the proximal external iliac artery and two 2.5 cm lymph nodes were seen anterior to the distal external iliac artery. On excision biopsy, the largest inguinal lymph node showed reactive follicular hyperplasia with extensive sinus histiocytic reaction. The histiocytes were eosinophilic, containing black foreign material (Figure 1) and birefringent particles in similar distribution (Figure 2). No malignancy was identified. The patient remains fit and well and the lymphadenopathy has regressed slightly.
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COMMENT
Osteoclastoma or giant cell tumour of the bone comprises about 6% of all primary bone tumours.1 Around one-tenth of these are malignant at presentation and malignant transformation is possible.
Orthopaedic endoprostheses generate wear particles including cement, polyethylene and metal at their component interfaces.2 Deposition of these wear particles in the soft tissue surrounding the prosthesis is believed to be important in the pathogenesis of prosthesis loosening, but the draining lymph nodes are seldom palpably enlarged. Gray et al.3 described two cases of histologically abnormal lymph nodes following joint replacement. The nodes were sampled in one patient during surgical staging for prostatic carcinoma and in the other during joint replacement revision surgery. In both, the lymph node sinuses were dilated and packed with macrophages containing eosinophilic granules that stained intensely with periodic acid/Schiff. Fragments of foreign material were seen on polarization microscopy. These samples, unlike those of our patient, did not show reactive lymphoid hyperplasia.
Lymphadenopathy with sinus histiocytosis is seen in various conditions benign and malignant, including metastatic carcinoma. The important differentiating factor in our case was the black material, with particles 0.5-5 µm in diameter within the histiocytes. These were probably metal. Polyethylene particles impart an eosinophilic granularity to the cytoplasm but are colourless and difficult to identify except under polarized light, when they show birefringence.3
The importance of removing and examining enlarged lymph nodes in these circumstances was underlined in a case report by Digby:4 the patient had lymphadenopathy after silicone MCP joint replacements, and the cause proved to be undifferentiated large cell lymphoma with incorporated silicone particles. In the present case the outcome was happier.
Acknowledgments
Our thanks to Mr J Miller, consultant orthopaedic surgeon, Mayday Hospital, and Mr Bob Chapman, Pathology Photography, Charing Cross Hospital.
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