MACRODYSTROPHIA LIPOMATOSA- A RARE CASE REPORT

Xiaoming Zhu , Yongfei Wang , Xuelan Zhao, Cuiping Jiang, Qiongyue Zhang, Wenjuan Jiang, Yan Wang, Haixia Chen, Xuefei Shou, Yao Zhao, Yiming Li, Shiqi Li , Hongying Ye

Abstract: Macrodystrophia lipomatosa is a rare cause of congenital macrodactyly. It can be confused with other common causes like congenital lymphedema. Usually it presents with loss of function and cosmetic problems. We here report a case of “Macrodystrophia lipomatosa” who attended our college hospital with progressive disproportionate enlargement of the middle finger of left hand. She underwent debulking operation twice. The patient had no pain or neurovascular symptoms and there was no family history of extremity gigantism. Plain radiograph demonstrated splayed, elongated, broadened phalanx with soft tissue swelling along the volar and dorsal aspect of middle finger of right hand, along with palmer angulation of that finger. MR images revealed proliferation of fatty tissue in the same areas, as seen in plain radiograph with signal intensity similar to that of subcutaneous fat. Histopathology revealed abundant adipose tissue with some interspersed fibrous tissue.
Keywords: Macrodystrophia lipomatosa(MDL). Macrodactyly.
Introduction
Macrodystrophia lipomatosa (MDL) presents as localized gigantism of the hand or foot and comes to clinical attention because of cosmetic reasons, mechanical problems secondary to degenerative joint disease, or development of neurovascular compression due to large osteophytes.[1] Radiological investigations, especially MRI, help to make a definitive diagnosis noninvasively and to differentiate it from other causes of macrodactyly. We review the clinical and radiological features of MDL by describing two cases, both of which had involvement of the upper limb digits. In the first case, the pathology was confined to the thumb and index finger, while in the second case, the ring and little finger were involved, which is rarely reported in the literature.

Case report: An 16 years old right hand dominant female child was referred to radiology department for X-ray of left hand because of excessive growth of her middle finger that had enlarged gradually since birth. She had undergone two operations to debulk the lesion. The patient denied having any pain or neurovascular symptoms and there was no family history of extremity gigantism. On physical examination, non-tender, disproportionately enlargement of middle finger was found. There was no overlying cutaneous change, pitting edema or bruit. The patient was able to use the hand well and had adequate grip. A plain radiograph demonstrated splayed, elongated, broadened phalanx with soft tissue swelling along the volar and dorsal aspect of middle finger of right hand, along with palmer angulation of that finger. Extraction of fat was done through an incision placed over the dorsum of the middle finger. Pathological examination of the material revealed abundant adipose tissue with some interspersed fibrous tissue.

Both T1W andT2W MRI images revealed proliferation of fatty tissue on the volar and dorsal aspect of the middle finger with signal intensity similar to that of subcutaneous fat with palmer angulation of the affected digit.

Discussion:
Macrodystrophia lipomatosa (MDL) is uncommon, congenital, non hereditary localized gigantism involving usually 2nd or 3rd digits of hand or foot corresponding to the median and medial planter nerve supply upper and lower limb respectively5 . Occasionally it involved the entire limb. Macrodystrophia lipomatosa, this term was first used by Feriz in 1925 to describe unilateral overgrowth of the lower limb1 . In 1967 Barsky described it is worth nothing that MDL is essentially analogous to static localized gigantism5 . Though the exact etiology of MDL is not known, various hypothesis exist, including alteration of somatic cells during limb bud development, disturbed fetal circulation, variable form of neurofibromatosis, lipomatous degeneration, trophic influence of tumified nerve, in utero disturbance of growth limiting factor or an error in segmentation. It is usually diagnosed at birth or during the neonatal period 1,2,4 .
MDL is characterized by a marked increase all mesenchymal elements. This is dominated by adipose tissue in a fine network involving periosteum, bone marrow, nerve sheath, muscle and subcutaneous tissue1 . It is usually presents at birth and recognized associated anomalies include syndactyly, polydactyly, brachydactyly or clinodactyly. Association with small osseous protuberance, which resembles osteochondromas and lipoma in other parts of the body, has also been reported. The disease is almost always unilateral, with an equal incidence in males and female. The growth velocity may differ from digit to digit and the abnormal growth usually ceases at puberty. The lower extremity is frequently involved than upper extremity. The abnormal area is usually along a specific sclerotome1,5 .

Different imaging modalities such as plan radiography, USG, CT scan and MRI have a role in the evaluation of MDL. Plain radiography usually suffices and demonstrates splayed, lengthened and broadened phalanges called mushroom like appearance with periosteal and endosteal bone deposition1,5. The overlying soft tissues are markedly overgrown and within the soft tissues focal lucent areas representing fat may be seen, which is characteristic1,6. Both USG and CT scan can be used to demonstrate the proliferation of the fat along the nerve territory1 . MRI easily demonstrates the excessive fibro fatty tissue, which has signal characteristics similar to subcutaneous fat that is high signal on T1W, intermediate signal on T2W and low signal on fat suppressed sequences. The fat in MDL is not encapsulated. The fibrous strands within the fatty tissue are seen as low signal intensity linear strands on T1W images1 .
Histopathology shows an abundant increase in adipose tissue scattered in fine, mesh like fibrous tissue7 .
Differential diagnosis includes (a) Neurofibromatosis, (b) Fibrolipomatous hamartoma of the median or ulnar nerve, where fatty tissue accumulates within nerve sheath rather than in the region, (c) Vascular malformation like Haemangioma including Maffucci syndrome, arterio-venous malformation (AVM), KlippelTrenaunay-weber syndrome, (d) Chronic hyperaemia as in Juvenile rheumatoid arthritis, haemophilia, (e) Hemi-hypertrophy as in Beckwith Wiedemann syndrome and (f) Russel-Silver dwarfism5.
Although MDL is considered a progressive form of macrodactyly (i.e. the growth of the affected parts is faster than the rest of the body) the growth halts at puberty5 . Surgical intervention is the treatment of choice for MDL. The main surgical principle of treating these lesions is to improve the cosmetic appearance while preserving the neurological function as much as possible. Through judicious and planned multiple debulking operations and partial amputations, good results can be achieved. However, surgery should be delayed until the patient’s growth is complete, if the deformity is not very serious and if no neurological symptoms are present1 .
Complications of MDL include mechanical problems secondary to degenerative joint disease, or neurovascular compression due to large osteophytes. Overzealous debulking procedures can also lead to nerve injury, the reported incidence ranged from 30% to 50%. A localized recurrence rate is about 33% to 60% 1,7 .
Conclusion:
MDL is progressive hamartomatous enlargement of the fibro fatty tissue involving all the layers of soft tissue. The purpose of this case report is to create awareness that MDL should be considered in the differential diagnosis of progressive disproportionate enlargement of a finger. Plain radiography usually suffices. Both USG and CT scan can be used to demonstrate the proliferation of the fat along the nerve territory. MRI easily demonstrates the excessive fibro fatty tissue and the fibrous strands within. The diagnosis of the above described case is accomplished on the basis of clinical presentation and imaging findings on X-ray and MRI.

References:
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2. http://en.wikipedia.org/wiki/Macrodystrophia lipomatosa.
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