Case Report: Macrodystrophia lipomatosa – Illustration of two cases

Macrodystrophia lipomatosa is a rare cause of congenital macrodactyly, characterized by progressive proliferation of all mesenchymal elements, with a disproportionate increase in ﬁ broadipose tissue. This developmental anomaly is reportedly more common in the foot than in the hand, with a predilection for the plantar and median nerve distribution. We present two cases of MDL of the hand, one of which had an unusual nerve territory distribution, making clinical diagnosis difﬁ cult. Preoperative diagnosis was however made on the basis of radiography and MRI and was later conﬁ rmed on surgery

of the index Þ nger, and osteoarthritic changes in the distal interphalangeal joint [Figure 2].An MRI with a 1.5-T unit demonstrated increased fatt y tissue along the palmar aspect of the right index Þ nger and thumb, extending up to the thenar eminence.It was seen as a hyperintense area on T1W images with intermediate signal on T2W images [Figure 3].The underlying bones revealed normal signal intensity and intact periosteum.

Case 2
A 2-year-old right-hand-dominant male child presented with progressive enlargement and swelling of both dorsal Macrodystrophia lipomatosa (MDL) presents as localized gigantism of the hand or foot and comes to clinical att ention because of cosmetic reasons, mechanical problems secondary to degenerative joint disease, or development of neurovascular compression due to large osteophytes. [1]adiological investigations, especially MRI, help to make a deÞ nitive diagnosis noninvasively and to diff erentiate 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 Þ rst case, the pathology was conÞ ned to the thumb and index Þ nger, while in the second case, the ring and litt le Þ nger were involved, which is rarely reported in the literature.

Case Reports Case 1
A 7-year-old, right-hand-dominant male child presented with a progressive disproportionate enlargement of the thumb and index Þ nger of his right hand since 1 year of age.The patient denied having any pain or neurovascular symptoms and there was no family history of extremity gigantism.On physical examination, a nontender, soft tissue mass was palpable on the volar aspect of the enlarged Þ ngers and there was dorsal angulation of the index Þ nger [Figure 1].There were no overlying cutaneous changes, pitt ing edema, or bruit.The patient was able to use the hand well and had an adequate grip.A plain radiograph demonstrated soft tissue swelling along the volar aspect of the thumb and index Þ nger, an enlarged distal phalanx

Abstract
Macrodystrophia lipomatosa is a rare cause of congenital macrodactyly, characterized by progressive proliferation of all mesenchymal elements, with a disproportionate increase in fi broadipose tissue.This developmental anomaly is reportedly more common in the foot than in the hand, with a predilection for the plantar and median nerve distribution.We present two cases of MDL of the hand, one of which had an unusual nerve territory distribution, making clinical diagnosis diffi cult.Preoperative diagnosis was however made on the basis of radiography and MRI and was later confi rmed on surgery.and palmar aspects of the left fourth and Þ ft h digits since birth [Figure 4].No tenderness, pitt ing edema, bruit, or skin changes were present and the movements of the digits were normal.A radiograph revealed disproportionately enlarged left ring and litt le Þ ngers; there was soft tissue swelling, along with dorsal angulation of the fourth Þ nger and lateral angulation of the Þ ft h Þ nger [Figure 5].MRI depicted fatt y tissue proliferation around the left fourth and Þ ft h digits, which was more along the dorsal aspect [Figure 6].There was no medullary or periosteal abnormality.

Discussion
MDL is an uncommon congenital, nonhereditary, localized gigantism involving the digits or extremities.This term was Þ rst used by Feriz in 1925 to describe unilateral overgrowth of the lower limb. [2]Though the exact etiology of MDL is not known, various hypotheses exist, including alteration of somatic cells during limb bud development and disturbed fetal circulation. [3]L usually presents at birth and may be associated with anomalies like syndactyly, polydactyly, brachydactyly, or clinodactyly. [4]Association with small osseous protuberances, which resemble osteochondromas and lipomas, in other parts of the body has also been reported. [5]The disease is almost always unilateral, with an equal incidence in males and females. [6]The growth velocity may diff er from digit to digit and the abnormal growth usually ceases at puberty.The lower limb is more frequently involved than the upper limb.The abnormal area is usually along a speciÞ c sclerotome.The second and third digits of the hands and feet are most frequently involved, corresponding to the median nerve and medial plantar nerve supply in the upper and lower limbs, respectively. [7]Involvement of the ulnar nerve distribution, as seen in our second case, is extremely unusual. [4]The soft tissue overgrowth is most marked at the distal ends of the digits on the volar aspect and results in dorsal angulation of the involved digit.
Diff erent imaging modalities, such as plain radiography, USG, CT scan, and MRI, have a role in the evaluation of MDL.Plain radiography reveals hypertrophy of soft tissue and bone, with translucencies in the soft tissue due to increased adipose tissue.The phalanges, especially the distal phalanx, are elongated, broad, and splayed, sometimes giving rise to a mushroom-like appearance.Secondary osteoarthritic changes like joint space narrowing, subchondral cysts, and osteophytes often develop in adolescence or early adulthood. [1]Both USG and CT scan can be used to demonstrate the proliferation of fat along the nerve territory. [8,9]MRI easily demonstrates the excess Þ brofatt y tissue, which has signal characteristics similar to subcutaneous fat, i.e., high signal on T1W, intermediate signal on T2W, and low signal on fat-suppressed sequences.The fat in MDL is not encapsulated.The Þ brous strands within the fatt y tissue are seen as low-signal-intensity linear strands on T1W images.
The diff erential diagnoses of MDL and macrodactyly include neuroÞ bromatosis, hemangiomatosis, lymphangiomatosis, Proteus syndrome, and fibrolipomatous hamartomas.Neurofibromas show marked hyperintensity on T2W images and are seen in close relation to nerves.A positive family history, presence of cutaneous lesions, and bilaterality favor neuroÞ bromatosis, while hypertrophy along a nerve territory, unilaterality, and demonstration of fat within the nerve sheath on MRI favor MDL. [10]Lymphangiomas are hyperintense to muscle on T1W and hyperintense to fat on T2W images.Clinically, diff use swelling and pitt ing edema are found. [8]In hemangiomatosis, a bruit may be palpable clinically and, on MRI, long TR/TE sequences show a septate conÞ guration of high-signal-intensity channels, corresponding to the vascular channels and Þ brous strands found in hemangiomas.Osseous growth is not seen in both lymphangiomatosis and hemangiomatosis. [8]Proteus syndrome presenting with hemihypertrophy may simulate MDL, but associated abnormalities like calvarial changes,  pulmonary cysts, pigmented nevi, and intra-abdominal lipomas help to arrive at the correct diagnosis.Some consider MDL to be a localized form of Proteus syndrome.Fibrolipomatous hamartoma (FLH) of nerve is a rare tumorlike condition in which mature fat inÞ ltrates the neural sheath, with the majority of the lesions occurring in the median nerve.Pathologically, in FLH, the deposition of fat is within the nerve sheath, while in MDL it occurs throughout the involved part of the digits/extremity.However, MDL may be an associated feature of FLH in as much as 30-66% of cases. [11]FLH may show a speckled appearance on MR, correlating with its histologically known architecture, i.e., neural fascicles separated by fat and connective tissue.
In conclusion, determination of the cause of macrodactyly is clinically diffi cult due to the many possible etiologies.However, appropriate imaging, particularly with MRI, can make the determination of the underlying process easier and can be of great help in arriving at a correct diagnosis.Imaging helps in diff erentiating MDL from other causes of localized hemihypertrophy, which have diff erent prognoses, complications, and treatment.

Figure 1 :
Figure 1: Case 1: Clinical photograph of both hands demonstrates the macrodactyly involving the thumb and index fi nger (black arrows) of the right hand and the dorsal angulation of the index fi nger (white arrow)

Figure 2 :
Figure 2: Case 1: Plain radiograph of both hands shows soft tissue swelling (arrow) on the palmar aspect of the affected fi ngers; the distal end is predominantly affected, with splaying of the phalanges

Figure 4 :Figure 5 :
Figure 4: Case 2: A clinical photograph of both hands shows enlarged ring and little fi ngers (arrows) of the left hand as compared to the normal right hand