Giant Chest Wall Metastasis of Rectal Adenocarcinoma with Multistructural Involvement.

: Colorectal adenocarcinoma typically metastasizes to the liver and lungs, with pleural, breast, or osseous involvement being exceedingly rare. Here, we report an unusual case of rectal adenocarcinoma metastasizing to the chest wall with simultaneous involvement of the lung, pleura, ribs, and subcutaneous breast tissue, forming a dominant giant metastasis (25 × 18 × 16 cm) accompanied by additional satellite lesions between the ribs and pectoral muscles, as well as intrapulmonary nodules. : The patient underwent radical resection including rib excision, followed by hyperthermic intrathoracic chemotherapy (HITHOC) with mitomycin. Chest wall integrity was restored using a synthetic mesh and titanium plating, ensuring both oncologic clearance and structural stability. Multimodal therapy also included neoadjuvant chemotherapy with bevacizumab, which was continued postoperatively. : This case underscores the critical role of a multidisciplinary strategy in managing rare and aggressive metastatic patterns of colorectal cancer. In selected patients, a combination of systemic therapy, extensive surgical resection, advanced reconstruction, and regional chemotherapy may offer the potential for short-term local disease control. The radical excision of the giant tumour enabled continuation of systemic therapy under the national drug programme, was associated with short-term local control, and improved the patient's quality of life.