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Clinical history
A 53-year-old obese man was transferred to the hospi- tal with new-onset seizures and a left frontal intracra- nial tumour diagnosed by a CT scan. The preceding medical history was significant for chronic obstructive pulmonary disease, asbestos exposure, 30 pack-years of tobacco use and chronic alcoholism.
On admission he was found to have possible sepsis, respiratory failure and severe hypoxaemia, and was placed on a mechanical ventilator. Urine cultures iden- tified a urinary tract infection due to Escherichia coli.
Electrocardiogram revealed inferior myocardial infarc- tion and chest X-ray exhibited possible bronchopneu- monic changes. MRI scans revealed a large cystic and necrotic left frontal mass, measuring 7.9 x 7 x 7 cm in the transverse, anteroposterior and cephalocaudal planes. There was heterogeneous enhancement. The tumour extended through the genu of the corpus callo- sum with moderate left to right frontal midline shift.
His clinical status was stabilised and he was transferred to the transitional care unit for craniotomy and tumour resection.
An image-guided left frontal craniotomy revealed a firm subdural tumour on the left frontal cortical sur- face that was resected en bloc, preserving the pial planes and stripping it from the falx cerebri.
Gross surgical neuropathology
The specimen consisted of multiple irregular frag- ments of white-tan rubbery tissue admixed with glob- ules of bosselated, white-tan rubbery tissue, measuring 14 x 11 x 5 cm in aggregate. Sections revealed central cystic degeneration surrounded by solid white tissue.
Also present was an irregular piece of tan mature bone that measured 3 x 2 x 1.5 cm. Sections of the bone revealed central cancellous bone surrounded by a rim of cortical bone.
Histology
Examination of H&E-stained sections of tumour revealed mature hyaline cartilage showing a distinct perichondrium, a basophilic matrix and clusters of lacunae arranged in a lobular pattern. Each lacuna was occupied by a single mature chondrocyte without nuclear atypia or binucleation. As noted on gross examination, there was central cystic degeneration and
coagulative necrosis of the cartilaginous matrix and chondrocytes. There was also focal mineralisation of the matrix and endochondral ossification forming mature, compact and trabecular bone surrounded by cortical bone. The bone trabeculae exhibited irregular lamellae of bone with lacunae containing osteocytes, and is separated by a labyrinth of interconnecting spaces containing a cellular bone marrow, some fibrous and adipose tissue. The bone marrow exhibited unre- markable trilineage haematopoiesis. The tumour was adherent to dura mater, but did not invade the brain parenchyma.
Diagnosis — intracranial mesenchymal osteochondroma
Osteochondromas are a benign cartilaginous neoplasm composed of mature hyaline cartilage with focal ossifi- cation. They are the most common benign bone tumour and account for 40% of the benign bone lesions in the Mayo Clinic series. Extraskeletal (mes- enchymal) osteochondromas are known to originate from non-skeletal or non-cartilaginous tissue.
Hypotheses advanced to explain this phenomenon include development from heterotopic cartilaginous cells or pluripotential mesenchymal tissue, cartilagi- nous metaplasia of clones of normal cells or cartilagi- nous metaplasia of fibroblasts activated by trauma or inflammation.
Intracranial osteochondromas are uncommon, solitary slow-growing tumours with a reported incidence of 0.1 - 0.2% of all intracranial tumours. The majority arise from the base of the skull originating from residual rests of primordial cartilage in basilar synchondroses entrapped during endochondral ossification of the skull base. It is therefore not surprising that these tumours occur most commonly in the middle cranial fossa where so many sutures converge.
Intracranial osteochondromas of the posterior fossa have been reported but are very rare. About 15% of intracranial osteochondromas arise supratentorially, typically attached to the falx in a frontoparietal loca- tion, as in the case presented here. They have also been reported to arise from cranial nerves, walls of the ven- tricles and from the choroid plexus. In some cases the tumours have occurred as components of disorders of
Case report
New-onset seizures
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generalised mesenchymal neoplasias including Maffucci’s syndrome and Ollier disease.
Intracranial osteochondromas can occur at any age, with a predilection for younger individuals.
Characteristically, the tumour grows slowly over many years and can attain a very large size without clinical symptoms, especially when supratentorial. Similar tumours arising from the base of the skull present ear- lier.
Typically, the histomorphology resembles mature hya- line cartilage without anaplastic proliferation of chon- drocytes or nuclear atypia, with a lobular arrangement of clusters of lacunae containing single chondrocytes.
The presence of central coagulative necrosis and cystic degeneration as seen in this case appear consistent with the tumour outgrowing the vascular supply and undergoing central degeneration.
Although a meningioma might be suspected from the imaging, the principal pathological differential diagno- sis is an osteochondroma versus a low-grade osteo- chondrosarcoma. The absence of cellular pleomor- phism, nuclear atypia and binucleate chondrocytes makes this diagnosis unlikely. Intracranial mesenchy- mal osteochondromas exhibit a benign clinical course.
Complete surgical excision is curative; however the critical location of skull base tumours may prevent total excision. In such situations, delayed growth of the residual tumour has been reported and surgical re- excision where possible is curative. Transition to osteo- chondrosarcoma has rarely been documented.
Contributed by Bennet I Omalu, Clayton A Wiley, Ronald L Hamilton, Division of Neuropathology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
Published online in February 2003.
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LETTERS TO THE EDITOR
Letter to the Editor
END-OF-LIFE DECISIONS
To the Editor: While supporting the South African Law Commission’s (SALC’s) initia- tive in proposing a law legalising the imple- mentation of voluntary termination of life by advance directives (Living Will) and other processes,1I share Theodore Fleischer’s concerns about marginalising families when such decisions are taken. I sense that respect for patient autonomy and his/her rights in terms of the Patient’s Rights Charter2may be a critical factor in influencing the SALC’s attitude.
Fleischer advances cogent reasons for not excluding the family who are in a position to provide input within the ‘broader context of the patient’s circumstances’.1Moreover, to exclude family members who have shared years of caring and concern for a loved one would deprive the patient of the important opportunity to share feelings and continued support.
Family members also need to be involved when end-of-life decisions are taken in respect of demented relatives. These patients cannot be expected, and are not legally competent, to make such decisions.
In these circumstances doctors frequently
are proactive in planning with family mem- bers what action to take in the event of life- threatening illnesses such as pneumonia.
The doctor’s epistemic authority2can serve as a guide to the family but doctors cannot be the sole arbiters or moral agents in such decision-making.
Translocated families pose their own unique problems when ageing parents are left alone after children and grandchildren emigrate. During times of illness it is com- mon practice for these family members to involve themselves in the medical manage- ment of their parents, often leading to con- flict with the attending doctor who per- ceives this as unnecessary interference.
These problems will inevitably be com- pounded should translocated families be marginalised in the emotionally charged setting of end-of-life decision-making.
M SILBERT
403 Sea Point Medical Centre Kloof Road
Sea Point
1. Fleischer T. End-of-life decisions and the law: a new law for South Africa. CME2003; 21:24.
2. Silbert M. The patient-physician relationship. SAMJ 2001; 91:616.
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