Giant cell tumor of the bone presenting as swelling of the thumb

Abstract

We describe a giant cell tumor in a 74-year-old man who presented with pain and swelling in the left thumb. Radiographs of the left hand showed some lytic changes at the tip of the thumb. Magnetic resonance imaging suggested the diagnosis of giant cell tumor, which was later confirmed by biopsy. A good treatment response was achieved with disarticulation of the interphalangeal joint and amputation of the distal phalanx of the left thumb.

Giant cell tumor (GCT) of the bone is known to be benign but can become locally aggressive with a high chance of recurrence.¹ It is a relatively common tumor (comprising 20% of all benign skeletal tumors) involving the epiphysis of tubular bones such as the femur, tibia, and humerus; 90% of lesions occur in long bones. GCT involving hand bones is relatively rare, accounting for only 1% to 4% of cases,² with the thumb being the most common location in the hand. When GCT occurs in the hand bones, the recurrence rate is higher than that at other sites.³ GCT mostly affects those in their 20s to 50s. Even though GCTs are benign, evidence suggests a high chance of significant bone destruction, local recurrence, and pulmonary metastasis. Around 1% to 4% of GCT cases were reported to metastasize to the lungs.^4,5 Lung metastasis resulted in death in 16% to 25% of cases.⁶ Therefore, timely diagnosis and aggressive treatment involving amputation of the involved hand bone is recommended to prevent local spread and lung metastasis.

CASE REPORT

A 74-year-old right-handed white man came to the clinic with new complaints of painful swelling in his left thumb for almost a month (Figure 1). The patient denied any history of trauma or surgery to his finger. The left thumb was erythematous, mildly tense, and swollen. He had a previous remote history of an unknown malignant neoplasm of the skin, actinic keratosis, seborrheic keratosis, hypercholesterolemia, diverticulosis of colon, insomnia, and a pulmonary nodule. He was referred to orthopedic surgery.

Figure 1.

Erythematous, mildly tense swelling at the tip of the left thumb.

An x-ray showed a soft tissue lesion in the left thumb. This lesion erupted from the tuft of the left thumb with cortical disruption. Overlying the bony changes, there was mild soft tissue fullness. Lytic changes were seen at the tip of the thumb. A chest radiograph showed no change in the size of his pulmonary nodule. Magnetic resonance imaging of the left thumb showed an expansile lesion involving the tuft of the distal phalanx of the thumb. The lesion was well circumscribed and demonstrated expansion and thinning of the cortex and homogenous postcontrast enhancement. This was interpreted as an osseous neoplasm. Biopsy confirmed the diagnosis, and the distal phalanx of the left thumb was excised. Microscopically, the tumor was composed of round to oval mononuclear cells interspersed with uniformly distributed osteoclastic giant cells (Figure 2). There was no evidence of recurrence 1 year after resection.

Figure 2.

Sheets of osteoclastic giant cells with intervening mononuclear cells, with black arrows indicating representative osteoclastic giant cells (400×).

DISCUSSION

GCT of the bone is extremely unusual in those older than 55.⁷ In addition, the small bones of the hand are a highly unusual place for GCT to occur, because it is mostly found at the ends of long bones. A history of previous malignancy and the location of symptoms in our patient raised suspicion for a malignant process. Morris et al found that 6.1% of malignant tumors of the hand were due to metastatic disease.⁸ According to Afshar et al, the thumb was the most frequently involved digit, and the distal phalanx was the most frequently involved bone for metastasis.⁹ Hand tumors are often misdiagnosed as an inclusion cyst, felon, or Paget’s disease.¹⁰ Cancers in the hand tend to manifest symptoms sooner due to the tighter compartments. The most common symptoms noted are pain, swelling, and early loss of motor or sensory function.

GCT of the hand bones is comparatively more aggressive and has a higher recurrence rate than GCT in other parts of the skeleton. Unlike in the long bones, GCT in hand bones occurs in the diaphyseal region and extends into the surrounding soft tissue, making it less amenable to simple curettage.² Even though GCT is not malignant, amputation is recommended due to its aggressive nature, significant soft tissue expansion, and tendency to recur. Treatment with only curettage or incomplete resection of GCT in hand bones will have a high chance of recurrence within a year. GCT has a high likelihood of metastasis to the lungs.⁵ In this patient, even though there was a history of a solitary pulmonary nodule in the right lower lobe of the lung, there was no significant change from the previous reports at the time of presentation.

GCT, which has a benign course 80% of the time, has evidence of 10% malignant transformation after radiation therapy and also spontaneous dedifferentiation into osteosarcoma without any radiation. The spontaneous transformation to osteosarcoma is due to the presence of a mesenchymal cell line in GCT. GCT has a 10% to 50% local recurrence rate. Few reports have described instances where multiple surgeries might convert a benign lesion into a malignant lesion. Management remains the same for a benign and malignant course of the disease due to its aggressive nature.