SOFT TISSUE PATHOLOGIES
Neural Origin
1. Sciatic Nerve Endometriosis (Figure 1)
Overview1:
· Endometriosis affects 1-5% of women in reproductive age group.
· Most commonly involves the ovaries or deep pelvic structures.
· Endometrial implantation of the nerves is very rare
· Sciatic nerve endometriosis manifests as cyclical episodes of radiating pain coinciding with menstrual periods
· MRI is imaging modality of choice (SI depends on time of menstrual cycle)
Closest Mimicker: Neurogenic tumour (Schwannoma/Neurofibroma)
Imaging pearls
MRI
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Sciatic Endometriosis
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Nerve Sheath Tumor
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T1W
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↑ or ↔
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↓
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T2W
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↓ or Mixed
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↑
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Special Features
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Hemosiderin rim
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Target sign
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Post Gd
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Perineural
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Intralesional
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↓=Hypointense; ↑=Hyperintense; ↔ = intermediate
2. Fibrolipomatous Hamartoma of median nerve (Figure 2)
Overview2:
· Rare disease occurring in children or young adults
· Anomalous growth of fibroadipose tissue of the nerve sheath
· Median nerve involvement is commonest (80%) followed by Ulnar and Radial nerves
· Soft,
slowly enlarging,
mostly asymptomatic mass since infancy
· Pain,
paresthesia or carpal tunnel syndrome (occasionally)
· Associated with macrodystrophia lipomatosa (20-66%)
· Preferred management is conservative
Imaging Pearls
Ultrasound
Hypoechoic coaxial cabling encased by an echogenic substratum
MRI
MRI features are often pathognomonic and typically shows a coaxial cable-like appearance on axial images and a spaghetti-like appearance on coronal images
- T1 - the neural bundles are hyperintense to muscle and the surrounding substratum is isointense to muscle
- T2 - fat components are high signal and fibrous components are low signal
Pathologies of Subcutaneous soft tissues
3. Morel-Lavallée Lesion (Figure 3)
Overview3:
· Haemolymphatic masses associated with degloving injuries in severe trauma
· Skin and subcutaneous fatty tissue are sheared off abruptly from underlying deep fascia
· Resolves spontaneously or through simple drainage
· Trochanteric region of femur and proximal thigh are classical locations
Imaging pearls:
· USG:Anechoic/Hypoechoic elleptiform lesion; Internal echoes/fat globules ±; Fluid/Fluid levels±
· MRI: Divided into six types using Mellado-Bencardino classification:
Mellado-Bencardino classification
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T1W
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T2W
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Capsule
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Enhancement
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Shape
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Type I
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↓
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↑
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Occasional
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Nil
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Laminar
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Type II
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↑
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↑
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Thick
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Variable
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Oval
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Type III
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↔
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Mix↓+↑
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Thick
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Internal+ peripheral
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Oval
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Type IV
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↓
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↑
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Absent
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Variable
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Linear
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Type V
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Variable
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Variable
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Thin/Thick
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Internal+ peripheral
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Round
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Type VI
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Variable
|
Variable
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Thick
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Internal +peripheral
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variable
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↓=Hypointense; ↑=Hyperintense; ↔ = intermediate
4. Calcinosis universalis: (Figure 4)
Overview4:
· Most cases are idiopathic or in association with dermatomyositis (40%),
Reynolds disease.
· Sheet like calcium deposition occurs in deep fascia,
subcutaneous tissue,
muscles
· In cases associated with dermatomyositis four patterns of calcification are described:
- Superficial nodular/clump like calcific masses
- Deep calcareal masses
- Linear sheet like fascial calcifications and
- Diffuse lace like or reticular calcification
· Ulcer formations with extrusion of calcareal masses
· Acro osteolysis,
chest infiltrates ±
Closest Mimicker:
Myositis ossificans progressiva:
Imaging pearls:
X Ray/CT
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Calcinosis universalis
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Myositis ossificans progressiva
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Calcification pattern
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Sheet like (commonest),
nodular,
calcareal masses,
lace like
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More clumps than sheets
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Ulcers with extrusion of calcium
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May be present
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Does not occur
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Ossification
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Does not occur
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Occurs
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Zoning in calcium deposits
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Not seen
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Occurs
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5.Parry Romberg syndrome (Progressive hemifacial atrophy) (Figure 5)
Overview5:
· Sporadic and rare condition
· Insidious but progressive hemiatrophy of the face in a span of 2–20 yrs
· Atrophy involves skin and subcutaneous tissues with variable involvement of underlying muscular,
cartilaginous,
osseous structures
· Typically begins in the maxillary or periorbital region and may involve the forehead
Imaging Pearls:
· Facial hemiatrophy with obliteration of fat planes
· Enophthalmos
· Intracranial findings:White matter hypodensity (CT) or T2 hyperintensity (MRI);Subcortical calcification; ipsilateral brain atrophy
6. Kippel Trenaunay weber (KTS) syndrome (Figure 6)
Overview6:
· Sporadic,
rare disease with incidence of 1 in 1,00,000
· Characterized by a triad (at least 2 are required for diagnosis) :
- Soft tissue or bony hypertrophy of extremity (localized gigantism)
- Venous malformations/varicosities
- Capillary hemangioma (port wine strain)
· Single incompetent vein (vein of Servelle) from ankle to the infra-inguinal region may be seen (70% cases)
· If both arterial & venous malformations are seen together,
it is called Parkes- Weber Syndrome
· Visceral manifestations: pelvic vascular malformations may occur causing hematuria or rectal bleed
· Hip dislocation ± (sec to limb length discrepancy)
Imaging pearls:
· Radiology findings are reflective of underlying clinical manifestations
· Limb Varicosities,
vein of Serville seen on Color Doppler,
· MRI with Angio can show both Limb hypertrophy and vascular abnormalities
Pathologies of Muscles
7. Parsonage Turner syndrome (Figure 7)
Overview7:
· Rare disease with incidence of 1.6 in 100,000
· Also known as paralytic brachial neuritis
· Commonly affects males in 3rd to 7th decades
· Severe onset of non traumatic shoulder pain with weakness or paralysis
· Suprascapular nerve is involved (50%); Axillary and subscapular nerves may be involved too
· Self limiting disease; 90% recover completely in 3 years time
Imaging pearls:
MRI
· Denervation changes of shoulder girdle muscles
· T2W: increased signal intensity in involved muscles in initial stages
· T1W:atrophy with fatty infiltration in later stages
8. Nodular fasciitis8 (Figure 8)
Overview8:
· Scantily reported in Radiology literature
· History of minor antecedent trauma
· Average age of presentation is 33 years
· Distribution can be in subcutaneous,
intramuscular or intermuscular compartments
· Volar aspect of forearm is most commonly involved site (45%) followed by trunk (20%),
head & neck (18%) and lower extremity (16%)
· Histopathological diagnosis is very challenging as it closely resembles sarcoma
Imaging pearls:
Small size,
ovoid shape,
well demarcated borders
MRI: T1W ↔ to muscle; T2W ↑ or ↓ (in highly collagenous lesions),
inverted target sign (central high T2 signal) ±; trans-compartment spread may occur
Cortical avulsive injuries
9. Bufkin lesion(Figure 9)
Overview9:
· Do not touch lesion occurring in young and adolescent males
· Avulsive cortical irregularity posteromedial aspect of femoral metaphysis due to chronic traction by adductor magnus or medial head of gastrocnemius
· Diagnosis should be made noninvasively by clinico- radiological evaluation
· Histologically it may be confused with osteosarcoma/fibromatosis/fibroma
Imaging Pearls
· Radiographs/CT: Saucer shaped cortical defect with cortical irregularity and no soft tissue mass
· MRI: T1W↓ ; T2W↑ ,
No marrow changes/soft tissue,
Post Gd enhancement may be seen
Closest mimicker: Fibrous cortical defect (FCD)
Differential pearls:
· FCD migrates with bone growth whereas bufkin lesion does not
· Site of location of bufkins lesion (postero medial femoral cortex at muscle attachment site) is typical
· Bufkins lesions may be bilateral