Chapter 145 - Benign Soft-Tissue Tumors and Reactive Lesions Flashcards
Lipoma
age 40-60
MRI:
bright on T1
intermediate on T2
(these should look exactly like the surrounding fat on all sequences)
treatment: excisional biopsy/local excision if imaging is classic
Hibernoma
brown fat lipoma
slightly younger age group: 20-40
bright on T1, doesnt look exactly like surrounding fat on all the series
atypical lipomatous tumor
= well differentiated liposarcoma (when retroperitoneal)
very large, deep tumors
possibly with increased stranding on MRI
increased cellularity on Histo
!!! MDM2 expression !!!
tx = local excision
higher chance of recurrence than lipoma but no mets (retroperitoneal ones have increased likelihood of mets ~20%)
schwannoma (= neurilemmoma)
encapsulated, benign
age 20-50
males = females
NF2 tumor suppressor encodes schwannomin - related to Neurofibromatisis-2
occurs on the flexor surfaces, head, neck, pelvis
positive tinel
MRI:
low on t1
high on t2
path: grows eccentrically from nerve
S100+
treatment: intralesional excision
neurofibroma
age 20-40 (younger if related to NF-1)
mri: dumbbell shaped lesion expanding a nueral foramen
path: fusiform expansion of the nerve, unencapsulated, contiguous with the nerve fibers
interlacing bundles of elongated cells with wavy dark nuclei and wirelike collagen fibers
malignant transformation more common with plexiform neurofibroma
NF1, NF2 mutations
NF1: chromosome 17
NF2: chromosome 22
Nodular fasciitis
USP6 mutation! can see on FISH, self limited
20-40, males = females
rapid growth of lesion over 2-4 weeks, with h/o preceding trauma
volar forearm, back, chest wall, head/neck
MRI: extension along fascial planes and avid gad enhancement
path: super cellular with nodules on low power
plump fibroblasts arranged in short bundles or fascicles
tx: leave it alone if asx - often spontaneously resolve
intralesional or marginal excision
intramuscular myxoma
benign, non-aggressive, myxomatous soft tissue tumor
females 40-70
painless solitary large mass in thigh, buttock, shoulder, upper arm
HOMOGENEOUS on MRI
low on t1 (darker than mm)
bright on t2
Multiple intramuscular myxomas - mazabraud syndrome - fibrous dysplasia at similar sites when young
path: minimally cellular, loose reticular fibers
tx: marginal excision
Desmoid tumor
benign, locally aggressive, fibrous neoplasm
high risk of local recurrence
young people: 15-40yo
slight female predominance
mutations of B-catenin gene-> decreased wnt/bcatenin signaling
painless mass, rock hard, fixed, deep
shoulder, chest wall, back, thigh
mri:
low t1
low to medium t2
infiltrative within muscles
histo: bland fibroblasts, abundant collagen, uniform spindle cells with elongated nuclei, sweeping bundles of collagen
stains positive for beta caenin and estrogen receptor
tx = medical: tyrosine kinase inhibitor (sorafenib) = first line, tamoxifen, NSAIDs, COX inhibitors, standard chemo
elastofibroma
60-80, females?males
between scapula and chest wall
snapping scapula on exam, firm deep lesion
histo: elastic fibers with a beaded appearance and elastin staining
tx: nothing if asx, marginal excision if sx
glomus tumor
20-40
subungual region (1:4 male:female)
red-blue nodule, ridging on the nail, discoloration of the nail bed
paroxysmal pain, cold insensitivity, localized tenderness
MRI: low on T1, high on T2
histo: small vessels surrounded by glomus cells in hyaline stroma
tx: marginal excision
PVNS
cells overexpress CSF-1 (colony stimulating factor 1)
tumor cells recruit macrophages expressing the CSF1R
