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Giant cell tumor (GCT) of bone accounts for ∼ 5 % of primary bone tumors, however involvement of rib is uncommon. We here discuss a rare case of giant cell tumor of anterior arc of rib mimicking malignant breast mass with associated lung metastasis in a 28 year old woman. CECT and MRI revealed large soft tissue mass with epicenter at 3rd rib and erosion of 3rd rib. CECT also revealed lung metastasis. Histopathology confirmed the diagnosis of giant cell tumor.
Giant cell tumor (GCT) is primarily benign tumor but can be locally aggressive. It is characterized by multinucleated giant cells (similar to osteoclasts) in the background of stromal cells histologically. GCT occurs usually after physeal closure and radiologically appear as well defined eccentric lytic lesion in long bones extending to articular surface with a non sclerotic margin. Metastasis is uncommon and lung is the most common site. Rib is an uncommon site of presentation.
The main treatment is surgery but can recur after surgical resection. Denosumab (osteoclast activation inhibitor) is used for neoadjuvant chemotherapy.
We present a case of giant cell tumor of rib mimicking as breast lesion in a 28 year old woman with lung metastasis.
2. Case report
A 28 year old female presented to us with complaints of swelling in right breast region present since 1 year and was progressively increasing in size. Clinical examination revealed painless hard swelling in right breast and chest wall region. Histopathological examination of the mass has confirmed giant cell tumor (Fig. 1).
Fig. 1Hematoxylin and eosin (HE) stained sections show tumor fragments with hemorrhage (a, HE ×40) and many osteoclast-like giant cells (black arrows) (b, HE ×100). The mononuclear stromal cells show mild cellular polymorphism with round to oval vesicular nucleus and pale eosinophilic cytoplasm (c, HE ×400). The mononuclear cells are immunopositive for H3F3A (d, ×200).
Chest radiograph of the patient revealed large well defined lobulated mass in right hemithorax with subtle enlargement of anterior 3rd rib (Fig. 2a). Subsequently contrast enhanced CT chest was done, which revealed heterogeneously enhancing chest wall mass with epicenter at 3rd rib and associated large soft tissue mass with extrathoracic component (Fig. 2 [b-c]). Calcifications were also seen. It was seen compressing pectoralis muscle and causing contour bulge at right breast region. It was also abutting mediastinal structure including major vessels and heart. Lung metastasis was also found in subsequent CT (Fig. 2d). MRI revealed similar findings and showed large heterogenous chest wall mass with epicenter at 3rd rib with intrathoracic and extrathoracic soft tissue. It was isointense on T1 weighted images, heterogeneously hyperintense on T2 weighted images and showed diffusion restriction on diffusion weighted images (Fig. 3).
Fig. 2(a–d). Chest radiograph (a) shows large lobulated mass in right hemithorax. Subtle expansion of anterior 3rd rib is seen (arrow). CECT chest axial (b) and coronal (c) shows heterogeneously enhancing chest wall mass with epicenter at 3rd rib with associated large soft tissue mass (intra and extrathoracic component) with calcification within. It is compressing pectoralis muscle causing contour bulge (arrow) at right breast region. CECT chest (d) done on follow up, shows multiple lung metastases (arrows).
Fig. 3(a–d). MRI shows large heterogenous chest wall mass with epicenter at 3rd rib and concomitant soft tissue. It was isointense on T1 weighted axial image (a), heterogeneously hyperintense on T2 weighted image (b) and showed diffusion restriction on diffusion weighted images (c and d).
GCT accounts for ∼5 % of primary bone tumors and ∼20 % benign bone lesions. The common age of presentation is between 20 and 50 years with peak during 3rd decade (after physeal closure usually). Most common site of presentation is long bones (75–90 %). GCT can be associated with Paget's disease. Other less common sites include flat bones (pelvis, sacrum) and apophysis; with ribs, calvaria, scapula, hand and feet being uncommon locations.
It presents with non specific clinical features in the form of pain, swelling and restriction of movement. Pathological fracture can occur occasionally.
The typical imaging findings in radiograph include eccentric lytic lesion extending to articular surface with well defined (non-sclerotic) margin. MRI show nonspecific findings, usually low to intermediate signal intensity in T1 weighted image, high signal in T2 weighted images and contrast enhancement post gadolinium administration.
Scintigraphy using Tc 99m-methylene diphosphonate show peripheral increased radiotracer uptake with photopenic center usually. Less commonly, GCT may show aggressive imaging features with wide zone of transition, lack of trabeculation, expansile remodelling, cortical thinning with or without destruction and concomitant soft tissue. It can also show fluid-fluid levels due to secondary ABC formation. Metastases in uncommon (1–6% cases), most commonly to lung and are histologically benign.
The differential diagnosis of lytic lesions of rib include benign lesions like eosinophilic granuloma, brown tumor, aneurysmal bone cyst (ABC), simple bone cyst (SBC) and chondromyxoid fibroma and malignant lesions like expansile lytic metastasis (renal and thyroid carcinoma), solitary plasmacytoma and chondrosarcoma. Benign lesions are usually seen in adult in 2nd and 3rd decade and malignant lesions after 50 years of age. Eosinophilic granuloma can be solitary lytic lesion or have other lesion in calvarium, brown tumors are usually multiple with associated hyperparathyroidism, fluid-fluid level is seen in ABC (soft tissue is associated in secondary ABC), sclerotic margin is seen in chondromyxoid fibroma. Chondroid matrix is usually seen in chondrosarcoma.
Description of any subject overlap with previously published works
N/a.
Description of any conflict of interest or industry support of the project
N/a.
CRediT authorship contribution statement
Rupali Jain: Data collection, literature review, Formal analysis, Writing – original draft, intellectual critical review. Chandrashekhara S H: Data collection, literature review, Formal analysis, Writing – original draft, intellectual critical review. Asit Ranjan Mridha: Data collection, literature review, Formal analysis, Writing – original draft, intellectual critical review.
Declaration of competing interest
None.
References
Chakarun C.J.
Forrester D.M.
Gottsegen C.J.
Patel D.B.
White E.A.
Matcuk Jr., G.R.
Giant cell tumor of bone: review, mimics, and new developments in treatment.
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