A 6-month-old boy presented with gradual and progressive enlargement of the right upper limb since birth, especially the right hand involving the middle three fingers. He had difficulty in thumb opposition and resultant functional disability. There is associated clinodactyly of right thumb with syndactyly of the middle and ring fingers.
Radiograph demonstrated increased soft tissue component of right hand compared to the contralateral side, especially the middle three fingers with associated increase in the length and width of corresponding metacarpals and phalanges. There is syndactyly of the middle and ring finger with bony fusion of the distal phalanges.
MR and CT of the right upper limb revealed atrophy of the muscles of the arm and forearm with lipomatous hypertrophy of the subcutaneous tissue.
Background
Macrodystrophia lipomatosa (ML) is a rare congenital cause of limb gigantism due to hamartomatous growth of fibrofatty tissue involving single or multiple digits or the entire limb. It is interchangeably also called macrodactyly, digital gigantism, macromelia or limited gigantism [1].
Clinical Perspective
ML can present anywhere from neonatal period to late adulthood. The growth reaches a plateau at puberty. It commonly involves the lower limb, predominantly the medial aspect (along plantar nerve distribution). In the upper limb, involvement of lateral aspect is common (along the median nerve distribution) [2,3]. The primary pathology is increase in adipose tissue scattered in fibrous tissue, involving the bone marrow, periosteum, muscles, nerve sheaths and subcutaneous tissues with irregular enlargement of the median nerve in hand or plantar nerve in the foot [4]. Multiple periosteal nodules comprising chondroblasts, osteoblasts, and osteoclasts are seen coalescing towards distal ends of phalanges resulting in elongated phalanges with splayed distal ends.
ML patients usually present with cosmetic and mechanical problems. Soft tissue overgrowth is commonly seen in the volar aspect with dorsal deviation of the hand thus interfering with day-to-day activities. Also, mechanical problems like secondary osteoarthritis (reduced joint space, subchondral cysts, osteophytes) and compression of neurovascular structures can be seen (carpal tunnel/ tarsal tunnel syndrome) resulting in functional impairment [5].
Imaging Perspective
Radiographic findings of ML include excessive soft tissue and osseous overgrowth, radiolucent fatty areas and degenerative joint disease. Excessive bone growth and fat proliferation within muscle fibers are characteristic on CT. Widening at the distal end of the bones gives a characteristic mushroom-like appearance [6]. MRI can easily demonstrate fatty infiltration of muscles, hypointense fibrous bands, osseous hypertrophy and fibrous nerve thickening.
Outcome
Management aims at improving cosmetic appearance while preserving neurologic function. Surgical intervention is indicated depending upon the patient's symptoms, age, extent and severity of the disease. In a localized disease, ray removal is done. Other interventions like multiple debulking procedures, epiphysiodesis and various osteotomies are indicated for a more severe form of the disease. The surgical treatment is, however, quite challenging as despite adequate tissue removal, the difference in size may not be very apparent. Besides, the incidence of nerve injury following extensive debulking is approximately 30%-50% with a high recurrence rate of 33%-60% [7].
Take Home Message / Teaching Points
ML is progressive hamartomatous growth of fibrofatty tissue involving soft tissue and bone leading to localized gigantism. Diagnosis is made on the basis of clinical and radiological evaluation, which can be confirmed on histopathology. The management is mainly surgical but the outcome may not be very gratifying.
Macrodystrophia lipomatosa
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Based on the provided X-ray and MRI images of the right upper limb, the following key features are observed:
1. There is marked thickening of the soft tissues in the distal region (especially the wrist and hand), with increased volume most prominent in the middle three fingers and the palmar aspect.
2. X-ray shows bony overgrowth and elongation of the affected phalanges, with “mushroom-like” expansion of the distal phalanges.
3. MRI reveals an abundance of fatty signal in the affected area, which appears hyperintense on T1-weighted images and can also appear hyperintense on T2-weighted images, accompanied by fibrous band-like hypointense signals.
4. Irregular thickening around the neurovascular bundles within the soft tissue suggests fatty and fibrous tissue infiltration into nerve sheaths or muscle compartments.
5. Clinical photographs demonstrate an abnormal hand appearance with local hypertrophy, syndactyly of the middle and ring fingers, and mild thumb curvature (clinodactyly).
Considering the progressive enlargement of the right hand and upper limb from birth, alongside imaging findings and clinical symptoms, the following differential diagnoses are suggested:
1. Lipomatous Macrodactyly (Macrodystrophia lipomatosa, ML)
• Characterized by localized overgrowth of a limb or digit from birth or early childhood, often involving soft tissue, bone, and nerve sheaths. Imaging commonly shows an abnormal proliferation of adipose and fibrous tissue.
2. Proteus Syndrome
• May also present with asymmetric overgrowth of the trunk and limbs but is typically accompanied by multi-system abnormalities and other skin, skeletal, or vascular malformations, with more diverse clinical manifestations.
3. Neurofibromatosis
• While it can cause localized limb thickening or “pseudarthrosis” formation, it is often associated with café-au-lait spots and other hallmark signs. Imaging findings typically focus on neurofibromas.
4. Tumorous or Vascular Malformations (e.g., Venous Malformation, Lymphatic Malformation)
• Some vascular conditions can present as masses or limb overgrowth in infancy, but they usually exhibit specific abnormal vascular signals or enhancement patterns, rather than the prominent adipose proliferation noted in this case.
Given the characteristic congenital onset, progressive enlargement, concurrent soft tissue and bone overgrowth, and MRI findings (fatty and fibrous tissue hyperplasia), the most likely diagnosis is “Lipomatous Macrodactyly (Macrodystrophia lipomatosa).”
If clinical clarification is still needed, a pathological examination during surgery or biopsy can confirm the hamartomatous overgrowth of fat and fibrous tissue.
1. Treatment Strategy Overview
• Surgical Intervention: Surgical debulking or partial resection of phalanges (if volume reduction is needed) can be considered when functional limitations or cosmetic deformities are significant. For a 6-month-old infant, surgical timing typically requires thorough evaluation and consideration of developmental factors and parental preference.
• Early Functional Training: Collaboration with professional rehabilitation therapists can help address reduced hand mobility and grip strength. Gentle range-of-motion (ROM) exercises, mild muscle-strengthening activities, and sensory stimulation exercises may help maintain or improve joint flexibility and hand coordination.
• Regular Follow-up: Since growth may continue before puberty, periodic imaging and functional assessments are advised to guide adjustments in the intervention plan.
2. Rehabilitation/Exercise Prescription Recommendations (FITT-VP Principle)
Even at this young age, appropriate therapeutic exercises can help prevent severe contractures and loss of joint function:
• Frequency: 2–3 short sessions of joint movement exercises per day.
• Intensity: Primarily gentle passive movements and tactile stimulation, avoiding aggressive manipulation that may cause pain or injury.
• Time: Each session lasts around 5–10 minutes, modified according to the child’s tolerance, attention span, and emotional state.
• Type: Main activities include passive joint mobilization for the hand, gentle stroking, and simple grasp-encouragement exercises. Parents may also be encouraged to let the child grab toys during play if feasible.
• Progression: As the child grows and joint mobility evolves, more fine motor exercises (e.g., picking up small objects) can be introduced, while closely monitoring limb growth and adjusting training methods as needed.
This report is based on the existing clinical and imaging data for reference purposes only and cannot substitute for an in-person consultation or professional physician assessment. If you have further questions or need a detailed, individualized plan, please consult a specialist or professional rehabilitation team.
Macrodystrophia lipomatosa
