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Bone Case 13 Answers

1) Describe the abnormalities

i) There is an irregular area of raised uptake to the left of L2/L3, barely seen on the anterior images, suggesting a posterior paraspinal location.

ii) There is symmetric patchy increased uptake in the diaphysis and metaphysis of tubular bones along their cortical margin, best seen in the tibiae and fibulae, although the process affects the femora, feet, upper limb bones, scapulae, clavicles and spares the skull, ribs, spine and pelvis

2) What two processes are going on here?

i) On staging CT, the paravertebral abnormality was missed. However, on review, a 5cm heterogenous non-calcific mass in the paravertebral muscles at the L2/L3 level was demonstrated. Clinico-radiologically, this was felt to most likely to represent a metastasis.

ii) The other long bone findings are classic for hypertrophic osteoarthropathy (HOA), in this case a secondary paraneoplastic effect. The distinctive appearance of HOA is variously termed "parallel track", a "double stripe" or "railroad track" with a characteristic distribution of bony involvement predominantly in the axial skeleton, with a preference for distal metaphysis. Radionuclide bone imaging is a very sensitive method for detecting abnormalities of HOA. These scintigraphic findings frequently appear before plain film findings, correspond well with clinical manifestation and decrease after treatment.

3) How common are these processes in cases of carcinoma of the oesophagus?

(i) Muscular metastases. Although direct muscle invasion by carcinoma is well recognized, distant metastasis to skeletal muscle is uncommon. Autopsy series report a 0.8- 20.0% incidence of microscopic intramuscular metastases, though only a few cases of visible metastases to the muscle have been described in the literature. Muscle metastasis often remains asymptomatic, undetected by either physical examination or diagnostic imaging procedures. The reported incidence, therefore, might be rare because of a lack of recognition, underreporting, or infrequent autopsy evaluation for muscle metastasis. Furthermore, it may be that few patients with metastases to muscle survive long enough to allow clinical detection.

Nobody really knows why metastases to skeletal muscle are so rare as it has a rich vascular supply, Two thirds of all cancers metastatic to muscle are carcinomas, suggesting that the primary tumour morphology is important. It is vital to differentiate between a primary soft tissue sarcoma and metastatic disease as the treatment and prognosis are markedly different. Metastatic disease to soft tissue is uniformly associated with survival <12 months whereas a primary tumour may be amenable to curative resection.

(ii) HOA & Oesophageal carcinoma. HOA is rare in oesophageal carcinoma with only a handful of case reports.

Primary HOA is usually familial and occurs in pachydermoperiostitis. Secondary causes of HOA can be subdivided into pulmonary, pleural, cardiac, abdominal, and miscellaneous.

Pleural causes include pleural fibroma and mesothelioma. Pleural fibroma although rare, is the most common tumour to have associated HOA. Cyanotic heart disease with a right-to-left shunt is the only cardiac cause described. Pulmonary causes include bronchogenic carcinoma, Hodgkin's disease, metastases, emphysema and chronic pulmonary sepsis from TB, bronchiectasis, empyema, abscesses, cystic fibrosis, fungal infections and PCP infection. Abdominal causes include liver cirrhosis, ulcerative colitis, Crohn's disease, amoebic and bacillary dysentery, gastrointestinal tract polyposis, gastrointestinal tract neoplasms (gastric and pancreatic), lymphoma of the bowel, Whipple's disease, and biliary atresia. Miscellaneous causes include infected arterial grafts, tumours of the ribs, and nasopharyngeal and oesophageal carcinoma. One case has been reported in association with sarcoidosis in an adult and with malignant thymoma in a child.

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The text is entirely the opinion of the author and does not necessarily reflect that of RUH NHS Trust or the Bristol Radiology Training Scheme. Website content devised by Paul McCoubrie.