An Unusual Cause for Pulmonary Metastasis

Emil J Thachil*, Praveen Sreekumar*, Harilakshmanan**, Mohanan J Manjakara**, Anoop Kanaran**, Mohammed Musthafa***, Sooraj K P ****, Ravindran C *****

*Postgraduate Resident, Department of Internal Medicine, Medical College , Calicut.
**Postgraduate Residents,*** Senior Lecturer, ****Assistant Professor, *****Professor , Institute of Chest Diseases , Medical College, Calicut.

(Communications to Dr C Ravindran, Professor& Head , Institute of Chest Diseases, Medical College, Calicut,India
ravindranc@calicutmedicalcollege.ac.in )



Abstract

A young male developed a bony swelling on his right tibia which turned out to be a histologically benign giant cell tumor of bone. Months later he presented with extensive pulmonary metastasis.
Key words: Giant cell tumour
Pulmonary metastasis

Case summary

A 23 yr old male presented with dry cough, weight loss and dyspnoea on exertion for five months. Complaints started as a swelling of the right upper leg 7 months ago which gradually increased in size. The swelling was bony and painless. He had no other positive findings except for the mass in right tibia. X-ray of the right knee (Fig 1) showed a large, lobulated, eccentric, osteolytic lesion with well defined margins, cortical erosion and rupture of medial cortex with scanty periosteal thickening. Chest X-ray was normal.
He had a needle biopsy from the swelling which showed spindle shaped mononuclear cells and osteoclast type giant cells without pleomorphism and




Figure 1

was diagnosed as histologically benign giant cell tumor of the bone and was advised wide excision with arthrodesis. He refused and went for treatment with indigenous medicine. Two months later he reported with dyspnea on exertion and dry cough. There was loss of weight but no episode of haemoptysis. On further clinical and radiological evaluation the tumor was found to have involved the contralateral leg, lungs and mediastinal lymph nodes. There was no hepatic involvement. Sputum was negative for malignant cells. CXR (Fig 2) showed multiple nodules with calcification of varying sizes bilaterally with a huge mediastinal mass. CT of the right knee (Fig 3) showed a lytic lesion in the upper end of tibia, with cortical break and extension into the adjacent soft tissue with a similar tumor in the medial condyle of right femur. This was confirmed by an MRI of the right knee (Fig 4).

 

Figure 2

Bone scan demonstrated high uptake of tracer over the right tibia and right medial condyle of femur and also over the left tibia. He underwent an extended curettage of the right knee with cementing. The biopsy from the excised mass showed giant cell tumor of bone which was histologically benign. This benign nature was confirmed by consistent reports from 3 different labs.

 

Figure 3

Figure 4

CT of thorax revealed extensive lung involvement from metastasis and mediastinal lymph node involvement. Patient refused an FNAC from the lung mass. He was admitted for bronchoscopy. Although the mass causing extraluminal compression of the bronchus, was confirmed, biopsy could not be taken.

Figure 5

Discussion

Giant cell tumor (GCT) of the bone is a relatively uncommon benign, but locally aggressive bone tumor, accounting for about 5-10 % of primary bone tumors.7 The peak incidence is in the third decade of life, usually in the early 20s.1 There is a slight female preponderance.1 Mostly affecting a single bone, the most common sites include the distal femur, proximal tibia, and the distal radius.1 GCT typically involves the epiphysio-metaphyseal region of long bones and is eccentric. 1The tumor almost always extends up to the adjacent articular cartilage, which remains intact. [1]

Usually present as a painless swelling noticed either on physical examination or due to complicating fracture.1 Although benign, 0.5 - 2 % show metastases most commonly to the lungs.[1,7] In less than1% two or more bones [multicentric] may be involved.
Histologically the lesion is composed of osteoclast-like multinucleated giant cells with moderate vascularity and a network of proliferating round, oval or spindle shaped stromal cells. The actual tumor cells are the stromal cells whereas the osteoclast giant cells are 'reactive' cells7. Periosteal new bone formation is rare.

Metastatic lesions are generally identified years after the initial resection due to their extremely slow growth.6 they are usually solitary or few in number, are surgically resectable, and have histologic features identical to the primary tumor.

Dahlin described 407 cases of patients with giant cell tumor. Only eight of these patients developed pulmonary metastases. [1.9 %] 2 Campanacci et al reported 293 patients with giant cell tumors. Three patients developed histologically confirmed pulmonary metastases. Three additional patients had roentgenographic evidence of pulmonary metastases, but these were not proven histologically. [2.04%]. [3]

A sarcoma may occur in conjunction with a histologically benign GCT or it may develop at the site of a previously treated GCT after a prolonged interval, usually following irradiation. The malignancy is usually an osteosarcoma, a malignant fibrous histiocytoma, or fibrosarcoma.1 Also osteosarcomas can have giant cells, sometimes so many that the tumor resembles a giant cell tumor. However, they are usually situated metaphysially and show nuclear atypia and bone formation.[4]

X-ray appearance of GCT is usually an eccentric, lobulated, expansile, osteolytic lesion, with sharp, well defined margins, and extensive subchondral lysis. Peripheral bony ridges of the lobulated tumor give the radiographic appearance of trabeculations. These trabeculations appear as filigree of coarse to fine honeycomb-like patterns, so called 'Bubbly lesions'. Peripheral reactive new bone formation is rare. In thicker and wider long bones the tumor begins as intramedullary masses and grows eccentrically while in the thin long bones, such as the fibula or radius, most lesions are centrally placed. [1]
Pulmonary metastasis presents usually with solitary or few nodules of varying sizes, some of them showing dystrophic calcification. [5]

CT is superior to conventional radiography and tomography in outlining the extent of the tumor, especially its extra-osseous portion and its relationship to adjacent structures, as well as evaluation of cortical integrity and determination of tumor recurrence. MRI is currently the best imaging modality for GCT that allow accurate tumor delineation, although subtle cortical destruction is better demonstrated by CT. [1]

GCT shows increased uptake of Technitium-99m. The pattern of increased uptake may be diffuse (40%), or peripheral with little central activity (60%). Adjacent joints and soft tissues may also show an increased uptake and hence bone scan is non-specific and unreliable in defining the extent of the tumor.[1]

Intralesional curettage with autograft reconstruction by packing the cavity of the excised tumor with morselised iliac cortico-cancellous bone is the treatment of choice. This has a recurrence rate as high as sixty-percent. "Extended intralesional excision" with cementation using Polymethyl methacrylate (PMMA) has reduced the recurrence.1 Solitary or limited numbers of metastasis may also be treated with excision.



References
1. DN Pardiwala, S Vyas, A Puri, MG Agarwal: Pictorial Essay: Giant Cell Tumor of Bone: Ind J Radiol Imag 2001 11:3:119-126

2. Dahlin DC: Giant cell tumor of bone: highlights of 407 cases. Am J Radiol 1985; 144: 955-960.

3. Campanacci M, Baldini N, Boriani S, Sudanese A. Giant cell tumor of bone. J Bone Joint Surg Am 1987; 69A: 106-114.
4. Unni KK: How to Diagnose Malignant Giant Cell Tumor
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6. Fadare, Oluwole: Benign metastasizing giant cell tumor: Arch of Pathol and Lab Med: Sep 2002 .

7. Harris NH, Birch R,: Cysts and Tumors of musculoskeletal system: Clinical Orthopaedics; Kemp HBS, Pryle J, Stokes DT,981-1009.