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An unusual solitary osteochondroma arising from the first metatarsal bone
i-he i&i (lY97) 7.37-39 0 1997 Pearson Professmmi
Ltd
CASE REPORT
An unusual solitary osteochondroma arising from the first metatarsal bone P J. A. Molitor, Department
S. Myint
of Ovthopaedics, Scunthovpe General Hospital,
Scuntkorpe,
UK
SUMMARY Osteochondroma, the most frequently encountered benign bone tumour, is generally seen in the long bones. Tt is rarely found in the distal extremities. The following case is reported because it arises from a very rare site with atypical radiological features.
CASE REPORT
A 44-year-old civil engineer was admitted to hospital complaining of occasional tenderness and fullness over the plantar aspect of the left first metatarsal region of a few months’ duration. He denied significant trauma. Clinical examination revealed a non-tender hard mass over the plantar aspect of the first metatarsal region; plantar flexion of the left big toe was slightly limited at the first metatarsophalangeal joint level. Radiographs of the left foot showed an oval calcified mass on the plantar surface of the first metatarsal region (Fig. 1). A computed tomography (CT) scan was reported as highly suspicious of an osteochondroma which appeared to be connected with the first metatarsal head (Fig. 2). Surgery was performed through a plantar incision, which was deepened to expose the tumour. The intersesamoid ligament was divided to improve exposure of the stalk of the tumour, which was divided with an osteotome and the tumour shelled out. The residual tumour mass was resected with bone-nibblers. When palpated digitally, the area was found to be free of tumour. Post-operative progress was uneventful. Histology showed a benign osteochondroma or a parosteal osteochondromatous proliferation (Fig. 3). Because of the unusual clinical and radiological presentation, further histological opinions were obtained from other centres and reported as benign osteochondroma. Follow-up check X-rays of the left foot at 20 months after surgery showed no sign of recurrence (Fig. 4). Correspondence to Mr P. J. A. Molitor FRCS, Consultant Orthopaedic Surgeon, Scunthorpe General Hospital, Cliff Gardens, Scunthorpe DN15 7BH, UK
Fig. I-Pre-operatwe
X-rays
of left foot.
DISCUSSION
Osteochondroma can be defined as a benign cartilage capped osseous projection protruding from the surface of the affected bone. Any bone formed in cartilage is susceptible to formation of an osteochondroma. Mirra states that the osteochondroma is caused by a developmental defect rather than true neoplasm and is thought to originate within the periosteum as a small cartilaginous nodule.’ Unlike
38
The Foot
Fig. 2-CT
reconstruction
Fig. 3-Histological
section
of the tumour
of the lesion.
arising
from the left first metatarsal
Low power
25x magnification.
true neoplasm, its growth usually parallels that of the patient and usually ceases when skeletal maturity is reached. Solitary osteochondroma is the commonest benign bone tumour. It is reported to represent from 35.8% (Dahlin & Unni 1986)2 to 43.8% (Schajowicz 1981)’ of all benign bone tumours. The true incidence is much greater than these figures suggest because many osteochondromata are asymptomatic and not seen by clinicians. Malignant transformation into a secondary chondrosarcoma is rare but it can occur in 1% (Schajowicz 1981y to 3.2% of patients (Dahlin & Unni 1986)’ with solitary osteochondroma, and 27.3% of patients with multiple osteochondromata (Dahlin & Unni 19X6).’ The recurrence rate after surgical excision is about 2% in the Mayo Clinic series (Dahlin & Unni 1986).’ The reported recurrent intervals in that series varied from 1 year to 26 years after
head.
Stain haematoxylin
and eosin.
surgery. Most authors agreed that failure to remove the entire cartilaginous cap or even its overlying periosteum is probably the basis for most of the recurrences. Also, solitary osteochondroma has been shown to regress rarely.4 Osteochondromata usually occur in long bones near the metaphyseal region. They rarely occur in the hands or feet and represent less than 1% of reported cases (Mirra 1980,’ Schajowicz 19813). In this case, it arose from the first metatarsal head region with atypical radiological appearances. The radiographic presentation of an osteochondroma is a lesion that protrudes from the host bone on a sessile or pedunculated bony stalk and points away from the adjacent joint. The cortex and spongiosa of the osteochondroma blend imperceptibly with the cortex and spongiosa of the host bone (Fig. 5). This is its key radiologic feature.’ These features were
An unusual solitary osteochondroma
Fig. &Post-operative
check X-ray
20 months
after surgery
absent in this case which seemed to arise directly from the cortical surface of the bone just proximal to the articular margin of the first metatarsal head with no alteration of the surrounding cortex. We believe this is the first reported case of solitary osteochondroma in the English literature that has arisen from a very unusual place with atypical radiological appearances. REFERENCES 1. Mirra J M. Bone Turnours, Philadelphia: JB Lippincott.
39
Diagnoses and Treatment 1980. 520-53 1.
Fig. 5-Classic osteochondroma.
and pathognomonic
radrologrc
features
of an
2. Dhalin D C, Unni K K. Bone Tumours. General Aspects and Data on 8542 cases, 4th edn. Springfield: Charles C Thomas, 1986: 18-32. 3. Schajowicz F. Tumour and Tumourlike Lessons of Bones and Joints. New York: Springer-Verlag. 1981: 121-132. 4. Sutton D. A Textbook of Radiology and Imaging Vol. 1,4th edn. Edinburgh: Churchill Lrvingstone. 1987: 161-163.
Ltd
CASE REPORT
An unusual solitary osteochondroma arising from the first metatarsal bone P J. A. Molitor, Department
S. Myint
of Ovthopaedics, Scunthovpe General Hospital,
Scuntkorpe,
UK
SUMMARY Osteochondroma, the most frequently encountered benign bone tumour, is generally seen in the long bones. Tt is rarely found in the distal extremities. The following case is reported because it arises from a very rare site with atypical radiological features.
CASE REPORT
A 44-year-old civil engineer was admitted to hospital complaining of occasional tenderness and fullness over the plantar aspect of the left first metatarsal region of a few months’ duration. He denied significant trauma. Clinical examination revealed a non-tender hard mass over the plantar aspect of the first metatarsal region; plantar flexion of the left big toe was slightly limited at the first metatarsophalangeal joint level. Radiographs of the left foot showed an oval calcified mass on the plantar surface of the first metatarsal region (Fig. 1). A computed tomography (CT) scan was reported as highly suspicious of an osteochondroma which appeared to be connected with the first metatarsal head (Fig. 2). Surgery was performed through a plantar incision, which was deepened to expose the tumour. The intersesamoid ligament was divided to improve exposure of the stalk of the tumour, which was divided with an osteotome and the tumour shelled out. The residual tumour mass was resected with bone-nibblers. When palpated digitally, the area was found to be free of tumour. Post-operative progress was uneventful. Histology showed a benign osteochondroma or a parosteal osteochondromatous proliferation (Fig. 3). Because of the unusual clinical and radiological presentation, further histological opinions were obtained from other centres and reported as benign osteochondroma. Follow-up check X-rays of the left foot at 20 months after surgery showed no sign of recurrence (Fig. 4). Correspondence to Mr P. J. A. Molitor FRCS, Consultant Orthopaedic Surgeon, Scunthorpe General Hospital, Cliff Gardens, Scunthorpe DN15 7BH, UK
Fig. I-Pre-operatwe
X-rays
of left foot.
DISCUSSION
Osteochondroma can be defined as a benign cartilage capped osseous projection protruding from the surface of the affected bone. Any bone formed in cartilage is susceptible to formation of an osteochondroma. Mirra states that the osteochondroma is caused by a developmental defect rather than true neoplasm and is thought to originate within the periosteum as a small cartilaginous nodule.’ Unlike
38
The Foot
Fig. 2-CT
reconstruction
Fig. 3-Histological
section
of the tumour
of the lesion.
arising
from the left first metatarsal
Low power
25x magnification.
true neoplasm, its growth usually parallels that of the patient and usually ceases when skeletal maturity is reached. Solitary osteochondroma is the commonest benign bone tumour. It is reported to represent from 35.8% (Dahlin & Unni 1986)2 to 43.8% (Schajowicz 1981)’ of all benign bone tumours. The true incidence is much greater than these figures suggest because many osteochondromata are asymptomatic and not seen by clinicians. Malignant transformation into a secondary chondrosarcoma is rare but it can occur in 1% (Schajowicz 1981y to 3.2% of patients (Dahlin & Unni 1986)’ with solitary osteochondroma, and 27.3% of patients with multiple osteochondromata (Dahlin & Unni 19X6).’ The recurrence rate after surgical excision is about 2% in the Mayo Clinic series (Dahlin & Unni 1986).’ The reported recurrent intervals in that series varied from 1 year to 26 years after
head.
Stain haematoxylin
and eosin.
surgery. Most authors agreed that failure to remove the entire cartilaginous cap or even its overlying periosteum is probably the basis for most of the recurrences. Also, solitary osteochondroma has been shown to regress rarely.4 Osteochondromata usually occur in long bones near the metaphyseal region. They rarely occur in the hands or feet and represent less than 1% of reported cases (Mirra 1980,’ Schajowicz 19813). In this case, it arose from the first metatarsal head region with atypical radiological appearances. The radiographic presentation of an osteochondroma is a lesion that protrudes from the host bone on a sessile or pedunculated bony stalk and points away from the adjacent joint. The cortex and spongiosa of the osteochondroma blend imperceptibly with the cortex and spongiosa of the host bone (Fig. 5). This is its key radiologic feature.’ These features were
An unusual solitary osteochondroma
Fig. &Post-operative
check X-ray
20 months
after surgery
absent in this case which seemed to arise directly from the cortical surface of the bone just proximal to the articular margin of the first metatarsal head with no alteration of the surrounding cortex. We believe this is the first reported case of solitary osteochondroma in the English literature that has arisen from a very unusual place with atypical radiological appearances. REFERENCES 1. Mirra J M. Bone Turnours, Philadelphia: JB Lippincott.
39
Diagnoses and Treatment 1980. 520-53 1.
Fig. 5-Classic osteochondroma.
and pathognomonic
radrologrc
features
of an
2. Dhalin D C, Unni K K. Bone Tumours. General Aspects and Data on 8542 cases, 4th edn. Springfield: Charles C Thomas, 1986: 18-32. 3. Schajowicz F. Tumour and Tumourlike Lessons of Bones and Joints. New York: Springer-Verlag. 1981: 121-132. 4. Sutton D. A Textbook of Radiology and Imaging Vol. 1,4th edn. Edinburgh: Churchill Lrvingstone. 1987: 161-163.