Giant Cell Tumor of Rib Arising Anteriorly as a Large Inframammary Mass: A Case Report and Review of the Literature

Introduction. Giant cell tumor of the bone is a rare benign lesion that infrequently affects the ribs, and if present, is usually located posteriorly. The rarity of this tumor poses diagnostic and therapeutic problems for physicians, especially when it is located in the anterior arc of the rib in close proximity to the breasts in female patients. Case Presentation. We report the case of a 32-year-old Asian female with a giant cell tumor of her anterior rib, presenting as a large inframammary mass. Computed tomography showed a tumor arising from the 7th rib anteriorly with marginal sclerosis, cortical destruction, and a soft tissue mass. She was treated with surgical resection, and the defect was reconstructed primarily. The surgical specimen measured 28.0 × 24.0 cm. The microscopic examination showed a large number of multinucleate giant cells scattered over the parenchyma. Patient recovered uneventfully and continues to be recurrence-free six years after surgical resection. Conclusion. We report the largest known case of giant cell tumor arising from the anterior aspect of a rib. We recommend including giant cell tumor in the differential diagnosis of chest wall masses especially in female patients, regardless of the size on clinical examination.


Introduction
Giant cell tumors (GCTs) of bone usually arise in the epiphyseal region of the limbs, and their occurrence in the ribs is unusual [1]. These are usually found posteriorly in the ribs (epiphysis of head and tubercle), and their presentation anteriorly is very rare [2]. Giant cell tumors of the anterior rib in close proximity to the breasts may pose diagnostic and therapeutic problems [3], which prompted us to report this unusual case.

Case Presentation
MK, a 32-year-old Asian female, was admitted to our surgical unit with the chief complaint of a slowly enlarging mass just below her left breast for past 4 years. The only associated symptom was mild occasional pain of recent onset. Clinically, the lump was approximately 20.0 × 15.0 cm, hard in consistency, mildly tender, and located anteriorly below the left inframammary fold (Figure 1). The margins were indistinct, and the surface was smooth with tense, patchily erythematous overlying skin.
Chest and abdominal radiographs showed a radiolucent shadow in the left lower chest region. Computed tomography of the chest ( Figure 2) showed a tumor arising from the 7th rib anteriorly with marginal sclerosis, cortical destruction, and a soft tissue mass. The patient was investigated to rule out hyperparathyroidism.
The tumor was excised along with the rib above and below and a length well past the tumor margin. The defect was reconstructed primarily, and the patient made an uneventful recovery. Histopathology reported a large lobular mass enclosing the rib and measuring 28.0 × 24.0 cm ( Figure 3). Cut section showed areas of necrosis, hemorrhage, and a gritty feel.
Microscopic examination revealed a large number of multinucleate giant cells scattered over the parenchyma (Figure 4). The stroma contained vesicular plump spindle

Discussion
Giant cell tumors of the bone account for 5% of all primary bone tumors [4]. Most (85%) occur in the long bones, and approximately 50% are found around the knee joint. Many large series have reported an incidence of around 1% in the ribs; after reviewing 15 cases, Gupta and Mittal show that most of these involved the posterior aspect of the rib [2]. Microscopically, the two basic components of benign GCTs are stroma and multinucleated giant cells; the stromal cells are mononuclear and may be spindle shaped, ovoid, or round, while the multinucleated giant cells may be so large that the numerous nuclei are almost uncountable.
Current methods available to treat GCT include curettage with or without the use of alcohol, liquid nitrogen, phenol or methylmacrylate or bone graft, and complete surgical resection of the affected segment of bone [8]. Excision is desirable as 10% of GCTs in ribs undergo malignant transformation [7], while radiation therapy is not recommended as most of malignant transformations are related to previous radiation therapy [4]. Thus en bloc excision is an appropriate treatment, and disease-free survival is directly proportional to negative resection margin [15]. Hutter et al. report that most recurrences (81%) appear in less than 2 years, and almost all have been manifested by 4 years. Thus at least 5 years of close followup are recommended. However, it has been reported that the course of a benign giant cell tumor undergoing malignant transformation may take longer than 5 years [5].

Conclusion
In conclusion, ribs are a rare site for giant cell tumor and when present most of these tumors are located posteriorly near the epiphysis of the rib. We report the largest known case of giant cell tumor located on the anterior aspect of rib that was successfully managed with wide excision and primary repair of the chest wall defect without any recurrence.

Consent
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editor-in-chief of this journal.