LETTER TO EDITOR
Year : 2000 | Volume
: 10 | Issue : 2 | Page : 113--115
Radiographic and CT features of macrodystrophia lipomatosa
Consultant Radiologist, Kalinga Hospital, Bhubaneswar, Orissa, India
Consultant Radiologist, Kalinga Hospital, Bhubaneswar, Orissa
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Patnaik S. Radiographic and CT features of macrodystrophia lipomatosa.Indian J Radiol Imaging 2000;10:113-115
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Patnaik S. Radiographic and CT features of macrodystrophia lipomatosa. Indian J Radiol Imaging [serial online] 2000 [cited 2019 Aug 22 ];10:113-115
Available from: http://www.ijri.org/text.asp?2000/10/2/113/30619
Macrodystrophia lipomatosa is a rare form of localized gigantism - a congenital overgrowth of all the mesenchymal elements of a digit with a disproportionate increase in fibroadipose tissue. It is also known by several other names - partial acromegaly, macrosomia, elephantiasis, megalodactyly, dactylomegaly, macrodactyly, macroceir, local gigantism and club finger/toe .
I recently came across one such case of localized overgrowth, which was subjected to radiological evaluation. A seventeen-year-old girl was referred for radiological investigation of a swelling in her right foot involving the second and third toes. The swelling had been noticed at birth and it progressed slowly over the last ten years. There was no local change in color, pain or constitutional symptoms.
Radiographs of the right foot [Figure 1] showed enlargement of the bony as well as soft tissue structures involving the second and third toes. The foot showed dorsal and medial angulation of the second toe. Soft tissue swelling was present all around but more so at the distal end of the digits. There was syndactyly of the soft tissue component of the second and third toes at the level of the proximal phalanges. There was no polydactyly. Serial axial CT scans of the foot [Figure 2] revealed that the swelling was confined to the second and third toes and the rest of the foot was normal. The swelling measured about 13 cm x 4 cm. There was overgrowth of both bony and soft tissue components. The phalanges of the second toe were enlarged. The attenuation value of the soft tissue ranged from - 70 to -85 HU suggesting normal fat tissue and this was uniform. The soft tissue distribution was typically more towards the distal end of the involved toes on the dorsal and volar aspects. There were no osteolytic or sclerotic lesions in the involved bones.
Macrodystrophia lipomatosa may be detected at birth or early infancy. With a few exceptions, the affected digits grow insidiously until puberty. Involvement is almost always unilateral. The areas of predilection are the segments supplied by the median or plantar nerves. In the foot, the second and third toes are most frequently involved and this was true for our patient too. Though the exact etiology is still unknown, several explanations have been proposed. These are: i) lipomatous degeneration, ii) disturbed fetal circulation, iii) error in segmentation, iv) trophic influence of a tumified nerve, v) in-utero insult to limb bud vi) in-utero disturbance of a growth limiting factor or vii) an atypical presentation of neurofibroma .
Radiographs of the affected digits typically reveal excessive growth of both bony and soft tissue structures. The soft tissue outgrowth is most marked at the distal end of the digits and on the volar aspect, producing the classical deviation. Lucent areas within the soft tissue may be observed. The involved phalanges are enlarged in both length and breadth with splaying at the distal ends (mushroom-like appearance). The inter-metatarsal or the inter-metacarpal space of the affected digits is often widened. Associated anomalies such as polydactyly, syndactyly, bradydactyly, symphalangism and thinning of metatarsal bones in the affected digits are also known. Gupta et al described radiological features in 23 patients and emphasized that the widened phalanges characteristically maintain their trabecular pattern . This finding was well seen in our patient too. Studies describing the CT features are scanty. CT is expected to show overgrowth of the bones as well as the soft tissues (predominantly normal adipose tissue) with a typical distal distribution. The overgrown soft tissue can be identified as normal mature adipose tissue. MR diagnosis of this entity has recently been well-described ,.
The radiological differential diagnosis includes neurofibromatosis, Ollier's disease, secondary hyperemia due to tumors such as hemangiomas and lymphangiomas, dactylitis, melorheostosis, Still's disease, Klippel-Trenaunay-Weber syndrome and Maffuci's syndrome . Neurofibromatosis may be the most difficult entity to differentiate. The anomaly is often bilateral and the distal phalanges are not always the most severely affected. The enlarged osseous structures in neurofibromatosis may show a wavy cortex and an elongated sinuous appearance. Plexiform neurofibromas can produce premature fusion of the growth plates. Moreover, other distinct manifestations elsewhere in the body are often present in neurofibromatosis . Absence of enchondromas excludes Ollier's disease. Hemangiomas, lymphangiomas and tumor-related hyperemia do not show osseous growth . Bony as well as soft tissue overgrowth is also seen in Klippel-Trenaunay-Weber syndrome and Maffuci's syndrome. Besides local gigantism, unilateral cutaneous capillary hemangiomas, arterio-venous malformations and varicose veins characterize the former. Associated visceral manifestations and the obvious cutaneous abnormalities help in its diagnosis. Maffuci's syndrome though resembles Klippel-Trenaunay-Weber syndrome does not show soft tissue varicosities. Moreover osseous enchondromas or cartilaginous "organ-pipe" deformities are characteristically seen in this rare syndrome . The patients with macrodystrophia lipomatosa often seek medical advice for cosmetic surgery. Hence a correct diagnosis and good pre-operative radiological work up including CT scan are helpful for the surgeon.
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