Malignant primary bone tumors of the thoracic wall are rare [1]. Chondrosarcoma (CS) was the third most common primary bone malignancy after osteosarcomas and multiple myelomas [2]. It arises from cartilage-producing malignant mesenchymal cells [3]. Frequently, chondrosarcoma occurred in long bones or the pelvis. Their localization in the rib is rare [3, 4]. Early diagnosis and surgical treatment with widely negative microscopic margins is considered the gold standard therapy and offers the best chance for cure.

Primary chest wall tumors account for 5% of all thoracic tumors and <2% of all primary tumors. They are benign (osteochondromas, chondromas, fibrous dysplasia, and desmoid tumors) as well as malignant chondrosarcomas and soft tissue sarcomas, among others. Chondrosarcomas are the most common malignant chest wall tumors & the third most common primary bone malignancy following multiple myeloma & osteosarcoma. [5]. Chondrosarcoma is a rare solid tumor, with an annual incidence of <0.5 per million people per year. It predominantly occurs in the pelvis and femur, occasionally occurs in flat bones such as the sternum and ribs, and rarely invades lung tissue. Chest wall chondrosarcomas represent only 5-15% of all chondrosarcomas [6-7]. We hereby report a case of giant chest wall chondrosarcoma in a female who initially presented as a case of possible carcinoma of the breast and could have been easily misdiagnosed and treated as carcinoma.

A 40-year-old female came to OPD with a painless, smooth, but firm right breast lump, observed by herself for the past 3-4 months. The lump was of insidious onset, slowly increasing, without any nipple discharge. She had normal menarche with no family history of breast or ovarian malignancy. She did not report ingesting any oral contraceptive pills.

History and Physical Examination

 Physical examination revealed a very firm lump (4x3 cm) in the right lower inner quadrant of the pendulous breast without any axillary lymph nodes. Lump had restricted mobility and was found to be fixed to the chest wall. It was found to be smooth, non-tender, and not associated with any nipple discharge/overlying skin changes (Figure 1).

Radiology

Ultrasonogram over the right breast swelling revealed a multiloculated, hypoechoic space-occupying lesion in the right breast (34 mm x 16 mm) with internal calcific foci. No ductal dilatation was seen. Additional mass was located deep to the pectoralis major muscle (bony origin).

A fine needle aspiration cytology of the right breast lump showed abundant chondromyxoid ground substance and scattered round to oval cells. These cells had small nuclei, bland nuclear chromatin, and pale vacuolated cytoplasm. A few cells show mild nucleomegaly and nuclear membrane irregularity (figure 2). The impression was myxoid mesenchymal neoplasm with no evidence of breast malignancy.  Subsequently, high-resolution computed tomography was performed that revealed a large irregular soft tissue density lesion (AP 100 mm x TR 80 mm x CC 78 mm) was found in the right lower anterior chest wall with intrathoracic extension and producing extrinsic compression of the anterosuperolateral surface of the right lobe of the liver and adjoining diaphragmatic surface. Adjacent ribs revealed lytic destruction. Amorphous calcifications were noted within the lesion.

Since MRI allows more accurate delineation of the tumor and helps determine the presence & extent of tumor invasion and tissue characterization, it was included in the investigation. MRI revealed a large space-occupying lesion, 10 cm x 8 cm, arising from the anterior end of the right 4th and 5th ribs. It appeared hypointense in T1WI and predominantly bright in T2WI/STIR. The outline was lobulated. It was abutting and compressing the right lobe of the liver. However, no evidence of invasion was detected (FIGURE 3). The impression was a large lobulated chest wall space-occupying lesion arising from the 4th, 5th, and 6th ribs compressing the liver and abutting the heart. The possibility of a cartilaginous tumor was suggested with chondrosarcoma as a likely possibility.

These imaging studies altered our plan of treatment altogether. The patient was informed about the retro-mammary lesion. After consultation with the cardiothoracic surgeon, excision of the mass with chest wall reconstruction was contemplated, keeping in mind the need to conserve the breast.

Surgical Procedure

 The lesion was approached with a submammary anterior approach & was found to be adhered to 4, 5, 6, and 7 ribs (FIGURE 4). Excision of the space-occupying lesion with a 3 cm circumferential clearance was done along with reconstruction of the chest wall defect over 4, 5, 6, and 7 ribs with a 12x9 cm titanium mesh (Figure 5).

Histopathology

 Multiple sections were examined. They show features of a tumor, such as an infiltrating growth pattern encasing pre-existing trabecular bone. The stroma is myxoid with areas of hyalinization. Mineralization of the matrix is seen in places. The chondrocytes vary in size with a moderate amount of eosinophilic cytoplasm and varying degrees of nuclear atypia. Binucleated cells were identified. Rare mitoses were noted. The impression was CONVENTIONAL CHONDROSARCOMA—GRADE 2 (Figure 6).

Fig.1: Physical Examination With Lump Marked

Fig. 2: FNAC

Fig. 3: FNAC Of The Lump with H&E Staining

Fig. 4: Intra Operative Picture Showing the Tumor Fig. 5:  Titanium mesh

Fig.6: Conventional Chondrosarcoma – Grade 2

Chondrosarcoma of the rib is an uncommon malignant tumor [8]. Chest wall chondrosarcomas can occur in the ribs, sternum, or both. Chondrosarcoma is frequently observed in men and the age group 30–60 years [9]. Differential diagnosis between metastatic carcinoma and primary soft-tissue tumor is critical because treatment and prognosis are markedly different. Malignant chest wall tumors are a heterogeneous group of tumors, including invasion from an adjacent tumor, primary tumor, and metastatic tumors. Invasions from adjacent tumors that occur in the lung or breast are relatively more common than others [10]. Primary chest wall tumors can be classified into bone or soft tissue tumors. A bulky mass invading adjacent structures without mineralization is suspected to be a malignant soft tissue tumor. In adults, malignant fibrous histiocytoma (MFH) is the most common. MFH arises in the deep fascia or skeletal muscle in elderly people. It is usually a painless mass regardless of how large it is. CT findings can reveal a heterogeneous enhancing or calcified mass. In consideration of pain, neurofibrosarcomas are suspected, but they are usually associated with neurofibromatosis type I. They grow along the major or medium-sized nerves, such as the sciatic nerve and brachial or sacral plexuses. Squamous cells may arise from luminal epithelial cells, myoepithelial cells, or ductal metaplasia [11]. SCC is characterized by numerous malignant squamous cells with keratinizing eosinophilic glassy cytoplasm, intercellular bridges, keratin debris, and background necrosis. To confirm the diagnosis, a surgical biopsy is mandatory.

Chest wall/retro-mammary lumps are ubiquitous & can even mimic a breast lump, thereby misleading the young clinician [6-7]. MRI of the breast has the highest sensitivity for breast cancer detection among current clinical imaging modalities and is indispensable for breast imaging practice [12]. Magnetic Resonance Imaging is superior to other modalities of imaging for the diagnosis of atypical breast lesions & should be considered seriously when conventional ultrasonography and Fine Needle Aspiration Cytology are inconclusive. Retro mammary lesions can be safely excised, & chest wall defects can be reconstructed nicely with a sub-mammary incision, thereby preserving the breast and femininity. [13]

It is important to keep in mind that a computed tomography (CT) scan is the best imaging of choice. Recommended to delineate intraosseous or extraosseous involvement and define vascular or neural involvement [8]. Surgery is considered the standard treatment with en-bloc resection and a sufficient margin (4 cm margin of normal tissue on all sides). Because chondrosarcoma is not responsive to chemotherapy and radiotherapy [8].

However, in most cases, complete resection of a large tumor results in a wide defect, requiring, most often, reconstructive surgery. In rare cases, chondrosarcoma could invade adjacent organs, necessitating major surgery. Such a case was reported by Abraham et al. [9]; pneumonectomy with thoracoplasty was done due to the extensive involvement of the chest wall and the lung parenchyma. In our present case, the tumor did not invade noble organs. However, surgery left a large defect, and this necessitated a reconstructive surgery. Chest wall reconstruction should include stabilization of the bony thorax and coverage of any soft tissue defect. To provide rigidity, the reconstruction defect should be done with a double sheet of polypropylene mesh with a thin layer of methyl methacrylate paste spread between. Soft tissue reconstruction covering the synthetic materials and skin defect is best accomplished by muscle and musculocutaneous flap [14].

The prognosis of chondrosarcoma is relatively good, with a reported 5-year survival rate ranging between 64 and 80% [15-16]. Most studies concluded that survival was influenced by tumor diameter <5 cm, tumor location, high histological grade, and quality of margins [17-18]. The largest study of chest wall chondrosarcomas, which included 96 patients, was reported by McAfee et al. [17]. In 10 years, recurrence had developed in 50% of patients who had local excision, compared to 17% of patients who had wide resection. The risk for developing local recurrence or metastasis formation depends on anatomical locations. It was higher when tumors were localized in sternal, scapular, clavicular, or vertebral [18].

Widhe et al. of the Scandinavian Sarcoma Group studied 106 consecutive patients with chest wall chondrosarcomas. The authors observed that prognostic factors for local recurrence included the surgical margin and histological grade, while prognostic factors for metastases included the histologic grade, tumor size, and local recurrence [16]. Fortunately, in our case there was no involvement of lung parenchyma, so a wide resection of all thoracic diseases with appropriate margins is the rule. There is no indication of neoadjuvant radiation or chemotherapy in a suitable surgical candidate with a resectable thoracic chondrosarcoma [15].

Generally, chondrosarcoma is radioresistant and chemoresistant [1-8]. However, some authors report that chemotherapy improved the survival rate in patients with dedifferentiated chondrosarcomas [19-20]. In addition, Andreou et al. [21] reported that patients with metastatic chondrosarcoma who received treatment with radiotherapy (RT) had longer survival than those who received best supportive care. The recent study of Imai et al. [22] considers that carbon ion radiotherapy treatment was a suitable option for unresectable chondrosarcoma.

Retro-mammary lesions should definitely be considered in the differential diagnosis of atypical presentations of breast lumps with non-conventional FNAC reports. MRI is an excellent modality for the evaluation of uncommon breast lumps. Mutilating mastectomy is not necessary for even large retro-mammary lesions. Chest wall reconstruction with titanium mesh is an effective method of reconstruction.

Conflict of interest statement/funding: No author has any conflict of interest of any kind for the submission. No funding has been received for the work submitted

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