Bone and Soft-Tissue Disorders
= benign nonreactive process involving an increase in number reminiscent of embryonic capillaries or veins
◊Most common benign soft-tissue tumor of vascular origin!
Prevalence: 1–2% of population (higher in premature infants); in up to 10% of whites
Histo: increased number of thin-walled vessels containing RBCs / transudate lined by flat monolayered endothelial cells; frequently with variable amounts of nonvascular elements (fat, smooth muscle, fibrous tissue, bone, hemosiderin, thrombus)
- Fat overgrowth may be so extensive that some lesion may be misdiagnosed as a lipoma!
Age: most common tumor of infancy; present at birth in 30–40% M÷F = 1÷3
Location: lower extremity (common), head & neck (mid cheek, upper lip, upper eyelid)
Site: any soft tissue (eg, muscle), tendon, connective tissue, fatty tissue, synovium, bone
Distribution: focal + localized / diffuse + segmental
- painless mass; red (superficial); flesh colored / blue (deep)
- multiple variable-sized phleboliths (frequent)
US:
- partially defined hypoechoic hypervascular solid mass
- mixed echogenicity ← reactive fat overgrowth
- intratumoral bright foci of variable size + posterior acoustic shadowing = phleboliths
- prominent vascular channels
- abnormal arterial signal of low resistance with continuous forward flow during systole + diastole
MR:
- mass of intermediate signal intensity on T1WI:
- serpentine / lattice-like enhancement
- mass of extremely high signal intensity on T2WI:
- heterogeneous hyperintensity ← reactive fatty tissue around neoplastic vessels / vessels filled with blood
- serpentine pattern + flow voids (DDx to rhabdomyosarcoma)
- well-defined / infiltrative margin
- foci of low SI on T1WI + T2WI ← phleboliths / calcifications / fibrosis
Prognosis: cellular proliferation + enlargement during 1st year of life
- CAPILLARY HEMANGIOMA (most common)
= small-caliber vessels lined by flattened epithelium
Site: skin, subcutaneous tissue; vertebral body
Classification:- Juvenile capillary hemangioma
- Verrucous capillary hemangioma
- Senile capillary hemangioma
- enlarged arteries + arteriovenous shunting
- pooling of contrast material
- CAVERNOUS HEMANGIOMA
= dilated blood-filled spaces lined by flattened endothelium
Site: deeper soft tissues, frequently intramuscular; calvarium
Age: childhood- phleboliths = dystrophic calcification in organizing thrombus (in nearly 50%)
- large cystic spaces
- enlarged arteries + arteriovenous shunting
- pooling of contrast material
Prognosis: NO involution - ARTERIOVENOUS HEMANGIOMA
= persistence of fetal capillary bed with abnormal communications of an increased number of normal / abnormal arteries and veins
Etiology: (?) congenital arteriovenous malformation
Age: young patients
Site: soft tissues- superficial lesion without arteriovenous shunting
- deep lesion with arteriovenous shunting
- limb enlargement, bruit
- distended veins, overlying skin warmth
- Branham sign = reflex bradycardia after compression
- large tortuous serpentine feeding vessels
- fast blood flow + dense staining
- early draining veins
- VENOUS HEMANGIOMA
= thick-walled vessels containing muscle
Site: deep soft tissues of retroperitoneum, mesentery, muscles of lower extremities
Age: adulthood- ± phleboliths
- serpentine vessels with slow blood flow
- vessels oriented along long axis of extremity (in 78%) + neurovascular bundle (in 64%)
- multifocal involvement (in 37%)
- muscle atrophy with increased subcutaneous fat
- may be normal on arterial angiography
Frequency: 10%
Histo: mostly cavernous; capillary type is rare
Age: 4th–5th decade; M÷F = 2÷1
- usually asymptomatic
- Vertebra (28% of all skeletal hemangiomas)
Prevalence: in 5–11% of all autopsies; multiple in ⅓
Histo: capillary hemangioma interspersed in fatty matrix
◊The larger the degree of fat overgrowth, the less likely the lesion will be symptomatic!
Age: any age; young adult; female
Location: in lower thoracic / upper lumbar spine
Site: vertebral body; may extend into posterior elements- mostly asymptomatic
- “accordion” / “corduroy” / “honeycomb” vertebra
= coarse vertical trabeculae with osseous reinforcement adjacent to bone rarefaction ← resorption caused by vascular channels (also in multiple myeloma, lymphoma, metastasis) - bulge of posterior cortex
- extraosseous extension beyond bony lesion into spinal canal (with cord compression) / neural foramina
- paravertebral soft-tissue extension
- lesion enhancement ← hypervascularity
CT:- polka-dot appearance = small punctate areas of sclerosis (= thickened vertical trabeculae)
MR:- high signal intensity on T1WI + T2WI ← amount of adipocytes / vessels / interstitial edema (CHARACTERISTIC)
- thick vertical struts of low SI
- rarely low / intermediate SI on T1WI (= less fat indicating a more vascular / more aggressive lesion)
NUC:- photopenia / moderate increase in radiotracer uptake
Cx: vertebral collapse (unusual), spinal cord compression - Calvarium (20% of all hemangiomas)
Location: frontal / parietal region
Site: diploe- <4 cm round osteolytic lesion with sunburst / weblike / spoke-wheel appearance of trabecular thickening
- expansion of outer table to a greater extent than inner table producing a palpable lump
- Flat bones & long bones (rare)
- ribs, clavicle, mandible, zygoma, nasal bones, metaphyseal ends of long bones (tibia, femur, humerus)
- radiating trabecular thickening
- bubbly bone lysis creating honeycomb / latticelike / “hole-within-hole” appearance
MR:- serpentine vascular channels with low SI on T1WI + high SI on T2WI (= slow blood flow) / low SI on all sequences (= high blood flow)
NUC (bone / RBC-labeled scintigraphy):- photopenia / moderate increased activity
Intracortical Hemangioma
Histo: expanded haversian canals containing dilated cavernous vessels
Location: tibia >femur, ulna, mandible
- intracortical osteolytic lesion with vertically aligned intralesional calcifications
- cortical thickening / periostitis
CT:
- hypoattenuating intracortical lesion with spotty internal calcification = “wire-netting” appearance
MR:
- hyperintense lesion with hypointense septa on T2WI
DDx: osteoid osteoma
Frequency: 7% of all benign soft-tissue tumors; most frequent tumor of infancy + childhood
Age: primarily in neonates
May be associated with: Maffucci syndrome (= multiple cavernous hemangiomas + enchondromas)
- intermittent change in size; painful
- bluish discoloration of overlying skin (rare)
- may dramatically increase in size during pregnancy
Location: usually intramuscular; synovium (<1% of all hemangiomas)
- nonspecific soft-tissue mass
- infiltrating lesion of serpentine vessels interdigitating with fibroadipose tissue (in cavernous hemangioma)
- may extend into bone creating subtle rounded / linear areas of hyperlucency (rare)
- ± longitudinal / axial bone overgrowth ← chronic hyperemia
- may contain phleboliths (30% of lesions, SPECIFIC)
- nonspecific curvilinear / amorphous calcifications
- may contain large amounts of fat → indistinguishable from lipoma
CT:
- poorly defined mass with attenuation similar to muscle
- areas of decreased attenuation approximating subcutaneous fat (= fat overgrowth) most prominent in periphery of lesion
MR:
- poorly marginated mass hypo- / isointense to muscle on T1WI
- interspersed areas of increased SI on T1WI in periphery of lesion ← fat extending into tumor septa
- well-marginated markedly hyperintense (“cystic”) mass on T2WI (← increased free water content in stagnant blood) with striated / septated configuration
- tubular structures with blood flow characteristics (flow void / inflow enhancement; avid contrast enhancement)
- foci of signal voids ← high-flow vascular channels / phleboliths / thrombi
- high-signal-intensity areas on T1WI + T2WI (= hemorrhage + fat deposition)
- internal fluid-fluid levels ← high proteinaceous / hemorrhagic content
US:
- complex mass
- low-resistance arterial signal (occasionally)
Juvenile Capillary Hemangioma
= STRAWBERRY NEVUS
Prevalence: 1÷200 births; in 20% multiple
Age: usually neonate within 1st week; apparent at birth in only 20%; M÷F = 1÷3 to 1÷5
Histo: neoplastic features of endothelial proliferation
Location: head and neck (60%) >trunk (25%) >extremity (15%)
- “strawberry marks” (= bright red protuberant compressible lesions) of face, scalp, back, anterior chest wall
Prognosis: rapid proliferation from 2–10 months; followed by variable period of stability; slow involution in 75–90% by age 7 years
Indication for imaging:
- deep hemangioma, compromise of airway, impaired vision, heart failure, thrombocytopenic coagulopathy
- flow voids (DDx to rhabdomyosarcoma)
- T1 shortening during involuting phase ← fatty replacement of nidus
Cx: necrosis of overlying skin / Kasabach-Merritt syndrome (during proliferative phase)
Rx: expectant observation, assurance to parents, steroids, transcatheter embolization
Synovial Hemangioma
= rare benign vascular malformation
Age: child, young adult
- joint pain, swelling ← repetitive bleeding into joint
Location: knee (60%), elbow (30%)
- phleboliths (not uncommon)
MR:
- lobulated intraarticular mass
- intermediate SI on T1WI
- marked hyperintensity on T2WI ← pooling of blood within vascular spaces
- linear hypointense structures on T2WI ← fibrous septa / vascular channels
DDx: hemophilic arthropathy (polyarticular)
Lobular Capillary Hemangioma
= PYOGENIC GRANULOMA
= relatively common acquired benign vascular neoplasm of skin + mucous membranes
Cause: presumed neoplastic process; NOT a reaction to trauma / infection
Path: well-circumscribed lesion with central vessel as branching point for capillary lobules
Histo: lobules of capillaries in an edematous fibromyxoid stroma containing elongated spindle cells with numerous mitotic figures
Average age: 38 (range, 15–60) years; M <F
Location: head, neck, upper extremity (esp. fingers)
- solitary rapidly growing bright red cutaneous mass
- commonly ulcerating + bleeding
US:
- well-defined mildly to moderately echogenic mass containing small hypoechoic foci
- prominent tumor vascularity with arterial waveform
MR:
- lesion isointense on T1WI + hyperintense on T2WI
- marked enhancement
DDx: true hemangioma, glomus tumor