Macrodystrophia Lipomatosa: An Unusual Cause of Localized Gigantism.

Macrodystrophia lipomatosa (MDL) is a rare congenital form of localized gigantism characterized by progressive overgrowth of all mesenchymal elements with a disproportionate increase in fibro adipose tissue. Here we report a case of 20 years old male who presented with history of painless gradual enlargement of entire left upper limb since childhood. Magnetic resonance imaging and histopathology confirmed the diagnosis of macrodystrophia lipomatosa. This condition has to be differentiated from other causes of localized gigantism, since these conditions differ in their course, prognosis, complications and treatment.

What was known?

Macrodystrophia lipomatosa is a rare congenital disorder of localized gigantism. It is characterized by overgrowth of all mesenchymal elements, particularly fat.

Introduction

Macrodystrophia lipomatosa is a nonhereditary isolated developmental anomaly, which results in overgrowth of all mesenchymal elements such as bones, fat, phalanges, tendons, nerves, and vessels.[1] Involvement is almost always unilateral and the growth of affected parts usually ceases at puberty. We report a case of macrodystrophia lipomatosa (MDL) with painless, gradual, diffuse hypertrophy of the entire left upper limb. After clinico-radiological workup, other causes of localized gigantism were ruled out, and provisional diagnosis of MDL was made, which was subsequently confirmed by histopathology.

Case Report

A 20-year-old young man presented with a history of painless, progressive enlargement of the entire left upper limb since childhood. The patient had difficulty in using his left upper limb for his daily activities. He became an introvert, depressed, and extremely concerned with the grotesque appearance of his limb which forced him to become a school drop-out at a very young age. The patient had first consulted a doctor for his problem only in his early teens, as he was hailing from a poor socioeconomic background. The patient reported that he had undergone limb reduction surgeries twice at the age of 13 and 18 years, respectively, the details of which are not known. There was no other significant history. On examination, the gigantism involved predominantly the radial aspect of the entire limb, including thumb, index finger, and thenar area with relative sparing of ulnar aspect [Figure 1]. The mid-arm circumference of the affected limb was 130 cm, which was 4 times more than that of the right side. The skin over the affected limb was thickened, nontender, and nonpulsatile. There were no associated nodules, café-au-lait spots, pitting edema, audible bruit, or thrill and dilated veins. The lower limbs and right upper limb were normal.

Figure 1

Localized gigantism of the left upper limb involving the radial aspect

The skiagram of the left upper limb showed asymmetrical soft tissue prominence on the lateral aspect of arm, forearm, and hand including first and second digits. Duplex scan showed no evidence of arteriovenous (AV) fistula, deep vein aplasia, or any other AV malformations. Magnetic resonance imaging (MRI) depicted an asymmetrical increase in fibro-fatty tissue, which appeared hyperintense in T1- and T2-weighted images with nonencapsulated fatty infiltration within deltoid muscle [Figure 2] and complete suppression on fat-suppressed sequences. There were no medullary changes. Enlargement of phalanges of the first and second digits was seen with degenerative changes [Figure 3]. Histopathology showed abundant mature adipose tissue scattered in fine mesh-like fibrous tissue and infiltrating the dermal connecting tissue [Figure 4].

Figure 2

Prominent fatty soft tissue on the lateral aspect (white star), with fatty infiltration within the deltoid (white arrow)

Figure 3

Enlarged index finger (white star) with degenerative changes involving interphalangeal joint (white arrow) of the left hand

Figure 4

Mature adipose tissue infiltrating dermal connective tissue (H and E, ×100)

Based on this clinico-radiological evidence and histopathology, diagnosis of MDL was made. Recurrence of growth after previous unsuccessful debulking surgeries, with severe functional and esthetic disturbances made the patient opt for left above elbow amputation and prosthesis insertion. Surgery was performed 6 months ago, and the patient is under evaluation by the orthotics team for prosthesis insertion.

Discussion

The term macrodystrophia lipomatosa was coined by Friez in 1925 referring to localized gigantism in the lower extremity only.[1] In 1968, Ranawat et al. accepted the term as also applicable to gigantism of the upper extremity.[2] The dramatic proliferation of fatty tissue associated with localized gigantism has been described under many names including partial acromegaly, macrosomia, elephantiasis, megalodactyly, dactylomegaly, and macrodystrophia lipomatosa.[13] MDL occurs most frequently in the distribution of median nerve in the upper extremity and plantar nerves in the lower extremity.[3] The lower limb is more commonly involved than upper limb and also distal limb involvement is seen predominantly.[45] The exact etiology is not known. The various hypotheses suggested include lipomatous degeneration, disturbed fetal circulation in utero, disturbance of growth-limiting factor, trophic influence of a tumified nerve, and an error in segmentation. As the patient grows, the deformity begins to mechanically interfere with joint function, vascular supply, and innervation. MDL comes to clinical attention because of cosmetic reasons, mechanical problems secondary to degenerative joint disease, or development of neurovascular compression due to large osteophyte.[3] Surgical treatment remains cornerstone in the management of these patients and is performed to improve the functional status as well as for esthetic and psychological indications. However, extensive surgery may lead to complications such as nerve injury in 30–50% of patients and also a recurrence rate of 33–60%.[4]

The differential diagnosis of MDL includes neurofibromatosis (NF) Type 1 (plexiform neurofibroma), proteus syndrome, fibrolipomatous hamartomas, Klippel–Trenaunay Weber syndrome, hemangiomatosis, lymphangiomatosis, and Maffucci syndrome.[5] Several investigators postulate that MDL is an expression of NF. This theory is supported by distribution on hand corresponding to the area of the median nerve, pathologic similarities between the two including neural enlargement, predominant involvement of mesenchymal elements under neural control, and the occurrence of macrodactyly in patients with NF.[6] However, MDL differs from NF in the lack of systemic abnormalities, absence of family history, disproportionate increase in adipose tissue, and difference in radiological appearance. Hemangiomatosis is diagnosed clinically with a palpable bruit, and lymphangiomatosis clinically presents with diffuse swelling and pitting edema with each of the above conditions having characteristic MRI findings. Proteus syndrome abnormalities include calvarial changes, pulmonary cysts, pigmented nevi, and intra-abdominal lipomas. Some even consider MDL to be a localized form of proteus syndrome.[7] Klippel–Trenaunay Weber syndrome clinically presents with limb hypertrophy, cutaneous hemangiomas, varicose veins and AV fistulas, which can be confirmed by duplex scan and MRI. Fibrolipomatous hamartoma is a tumor in which nerve sheath of an isolated nerve is infiltrated with fat and showing speckled appearance on MRI with the majority of lesions occurring in the median nerve.[8] Table 1 shows the characteristics of MDL in few patients with upper limb involvement reported in Indian population.

Table 1

Characteristics of macrodystrophia lipomatosa in few patients with upper limb involvement reported in Indian population

Conclusion

In patients with gigantism of extremity, a rare differential diagnosis of macrodystrophia lipomatosa should also be considered. Histopathology and MRI differentiate MDL from other causes of localized gigantism, since these conditions differ in their course, prognosis, complications, and treatment.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

What is new?

There are only a few cases of macrodystrophia lipomatosa reported in literature till date and to the best of our knowledge, no such reports in Dermatology journals. Hence, this case has been highlighted for its rarity and unique presentation.