Progressive enlargement of the great toe: diagnosis and discussion
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Progressive enlargement of the great toe: diagnosis and discussion Pieter Janse van Rensburg & Hassan Douis
Published online: 5 January 2008 # ISS 2007
Diagnosis Macrodystrophia lipomatosa.
Discussion Macrodystrophia lipomatosa is a rare developmental anomaly leading to localised gigantism due to overgrowth of all mesenchymal elements, but predominantly adipose tissue interspersed in a mesh of fibrous tissue [1]. Originally described in the lower extremity, the definition now applies to the upper extremity as well. True macrodactyly is in fact very rare and is a congenital anomaly characterised by an increase in the size of all elements of a digit or digits [1]. Neurofibromatosis, Proteus syndrome and macrodystrophia lipomatosa are included in this category. Macrodystrophia lipomatosa may involve the bone marrow, periosteum, muscle, nerve sheaths and subcutaneous tissues [1]. The condition is not hereditary and is usually recognisable during the neonatal period. Unilateral involvement is the norm, although one or more adjacent digits in the same extremity may be involved [2]. The lower extremity is more commonly involved than the upper and it The case presentation can be found at http://dx.doi.org/10.1007/ s00256-007-0431-2. P. Janse van Rensburg (*) : H. Douis Department of Diagnostic Radiology, Faculty of Health Sciences, University of Stellenbosch, P.O. Box 19063, Tygerberg 7505, South Africa e-mail: [email protected] H. Douis University Hospital Birmingham NHS Trust, Birmingham, UK
often occurs in the distribution of the plantar or median nerves respectively. Neural enlargement, when present, is due to infiltration of the nerve sheath by fibroadipose tissue and not due to an increase in the number of axons [1]. Surgical correction may be motivated by cosmetic concerns. Complications due to compression of neurovascular structures or secondary osteoarthritis mostly present later. Digital overgrowth ceases at puberty [1]. On plain radiographs, prominent volar soft tissue overgrowth leads to dorsal deviation of the digit. Adipose overgrowth may be visible as lucencies in the soft tissues. The phalanges can be long and broad with distal splaying, as was the case in this patient. Slanting articular surfaces and secondary osteodegenerative changes may be evident [1]. As MRI can accurately depict adipose tissue it is of great value in confirming the diagnosis. It demonstrates excessive adipose tissue with normal subcutaneous fat signal intensity and fibrous strands as linear areas of low signal intensity on T1-weighted images. The adipose tissue suppresses homogeneously when a STIR sequence is applied. Muscular infiltration by adipose tissue, thickening of peripheral nerves, as well as osseous hypertrophy and cortical thickening, can also be detected [2, 3]. The differential diagnosis includes plexifom neurofibromatosis, Klippel-Trenaunay-Weber syndrome (macrodactyly with haemangiomas), lymphangiomatosis, haemangiomatosis, Proteus syndrome and fibrolipomatous hamartoma of the nerve [2, 3]. Neurofibrom
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