Uncommon metastases were diagnosed at anatomical sites such as the spinal cord,
kidney,
pancreas,
spleen,
peritoneum,
intestine,
corpus callosum,
orbit.
Spinal cord metastases:
Although spinal cord is not considered as a common metastatic site,
lung and breast cancers appear to be the most frequent source of intramedullary spinal cord metastases.
Cervical,
thoracic and lumbar spine are equally affected.
Symptoms include: motor weakness,
pain and sensory disturbance.
MRI is the imaging modality of choice.
Imaging findings include hyper T2 intramedullary lesions with enhancement.
At diagnosis,
most patients have a known primary cancer often associated with cerebral and other systemic metastases.
Overall survival is poor.
Figure 1 ( Fig. 1) shows MRI findings of thoracic spinal cord metastasis from small cell lung carcinoma.
Fig. 1: T1 weighted MRI after injection and T2 weihted MRI of thoracic spine show
intramedullary T2 hyperintense metastasis with post contrast enhancement from a small cell lung carcinoma
Renal metastases:
Renal metastases are a rare entity.
Lung cancer is the most prevalent primary tumor site.
CT is the imaging modality of choice for the diagnosis.
Ultrasound and MRI are less frequently used. Initial diagnosis typically results from routine imaging.
The imaging findings are not specific.
Unilateral renal metastases are more frequent.
Therefore,
differential diagnosis of primary renal tumor versus renal metastasis could prove difficult because of the lack of pathognomonic characteristics for a renal metastasis.
Figure 2 shows CT findings of renal metastasis from primary lung adenocarcinoma.
Fig. 2: CT shows renal metastasis from primary lung adenocarcinoma
Peritoneal and retroperitoneal metastases:
Peritoneum and retroperitoneum are a common location for metastases from tumors of the abdomen and pelvis,
less frequently from primary lung cancer.
Malignant involvement of the peritoneal lining occurs via haematogenous dissemination.
Peritoneal masses are usually asymptomatic,
diagnosed on routine CT imaging.
Imaging findings include single and multiple large enhanced masses.
Figure 3 ( Fig. 3 ) shows a case of peritoneal and retroperitoneal metastases from primary lung adenocarcinoma.
The patient also had pancreatic,
pleural and liver metastases.
Fig. 3: CT shows pancreatic, peritoneal and retroperitoneal metastases from primary lung adenocarcinoma.
Bowel metastases:
Small bowel metastases are rare and must be considered in patients with lung cancer and abdominal pain or acute abdomen.
Small bowel metastases are significantly associated with severe widespread metastatic disease.
Prognosis is poor.
Surgery is indicated for palliation.
Figure 4 shows ileal metastasis from primary lung adenocarcinoma.
Fig. 4: CT shows ileal metastasis from primary lung adenocarcinoma
Pancreas:
Pancreatic metastases are rare and account for less than 5% of pancreatic malignancies. However,
they must be considered if the patient has a history of lung malignancy.
Differentiating a pancreatic metastasis from a primary adenocarcinoma can be an imaging challenge.
Pancreatic metastases are most commonly from the lung,
followed by the gastrointestinal tract and kidney.
Figure 3 ( Fig. 3) shows a case of pancreatic metastasis from primary lung adenocarcinoma.
Spleen:
Splenic metastases have been reported from breast cancer,
lung cancer,
colorectal cancer,
ovarian cancer,
and melanoma.
Isolated spleen metastases are rare.
Figure 5 shows a spleen metastasis from squamous cell lung carcinoma.
Fig. 5: Spleen metastasis from squamous cell lung carcinoma
Corpus callosum:
Brain metastases rarely involve the corpus callosum.
Figure 6 (A-B) shows a metastasis to the corpus callosum from a primary lung carcinoma Fig. 6 .
Orbital metastases:
Orbital metastases are rare.
Most common presenting symptoms include diplopia,
exophtalmos and visual loss.
Figure 6 (C-D) shows orbital metastases from small cell lung cancer.
Fig. 6: 62 year old patient with small cell lung cancer
A-B T2 and T1 weighted MRI after injection show a metastasis to the corpous callosum
C-D Diffusion and T1 weighted MRI show left orbital enhanced mass.