Solitary Osseous Metastasis of Rectal Carcinoma Masquerading as Osteogenic Sarcoma on Post-Chemotherapy Imaging: A Case Report

Abstract

Solitary metastases from colorectal carcinoma in the absence of hepatic or pulmonary metastases are rare. These can have a diverse imaging appearance, particularly after chemotherapy. It is important identify patients with solitary skeletal metastases, as they have a better prognosis than those with multiple skeletal or visceral metastases. We describe an unusual case of a solitary metastasis to the femur in a case of colon carcinoma that went undiagnosed and later presented with imaging features of osteogenic sarcoma.

Colon adenocarcinoma first presenting as shoulder pain. Case report

“…Once detected they are usually multiple and occur late in the course of the disease, commonly indicating a bad prognosis, with a median survival of 5–7 months [ 5 ]. In contrast, it had been noticed that patients with isolated bone metastases have a significantly better prognosis than those with multiple skeletal or visceral metastases [ 6 ] and should probably be considered separately.…”

“…Osseous metastases usually involve the axial skeleton and the long bones. Some authors ascribe the higher incidence of skeletal metastases to the invasion of deep pelvic veins and dissemination via the paravertebral plexus of Batson, with the rectosigmoid colon being the primary site [ 6 , 8 ], although there are a few cases of long bone metastases from rectum cancer described in the literature [ 9 ]. This could be justified due to the connection with the iliofemoral veins.…”

Isolated Skull Metastasis With Unusual Spiculated Periosteal Reaction From Rectal Cancer Resembling Osteosarcoma on FDG PET/CT

“…Spiculated periosteal reaction is most often seen in aggressive primary bone sarcomas such as osteosarcoma and Ewing sarcoma 7 . However, occasionally, it may occur in metastatic bone tumors from a variety of malignancies including cancers of the thyroid, breast, bronchus, esophagus, stomach, colon, rectum, prostate, bladder, kidney, testis, and carcinoid and neuroblastoma and retinoblastoma 8–11 . FDG PET/CT is useful for detecting metastatic colorectal cancer lesions 12 .…”