Case 3 (b)

This post follows the previous one, where we were introduced to a 71-year-old man with symptoms and signs that were suspicious for colorectal cancer.

We left off with the question: what does the chest X-ray show?

The principle finding on the man's chest X-ray is multiple, well-defined, round opacities in each lung field. The most likely diagnosis here is multiple lung metastases. Other, less likely possibilities include infectious causes (multiple abscesses, septic emboli, fungal infiltrates), inflammatory diseases (rheumatoid nodules, nodules from Wegener's granulomatosis or sarcoid), or (rarely) pulmonary arteriovenous malformations.

Of course, we already had our suspicions as to where to go looking for the primary tumour. Nonetheless:

Question 4: In the context of multiple pulmonary metastases, what are the commonest primary sites?

The four most likely culprits are probably: bronchial, breast, gastrointestinal tract, and renal cancers.

The patient's full (complete) blood count came back as follows:

• White Cell Count: 9.0 x 10⁹/ L [Normal: 4-11]
• Haemoglobin: 7.7 g/dL [Normal: 13.5 - 16.5]
• MCV: 69 fL [Normal: 79-95]
• Platelets: 414 x 10⁹/L [Normal 150-450]

Question 5: Comment of the full blood count. What is the most likely cause of this abnormality?

The patient has a microcytic anaemia (with a normal white cell count and platelet count). The most common cause of this is iron deficiency anaemia. This ties in nicely with a possible diagnosis of colorectal carcinoma, since these cancers often bleed (usually microscopically) over many months, causing the loss of iron from the body.

The patient underwent a colonoscopy which showed what appeared to be a broad-based tumour at the splenic flexure. The subsequent histology report indicated it to be a colorectal adenocarcinoma. Prognosis is, sadly, poor.