Bone & Soft Tissue Pathology Flashcards
What sarcoma shows cytoplasmic but not nuclear WT1 expressin?
Rhabdomyosarcoma
What stain helps differentiate smooth muscle tumors from myofibroblastic tumors?
Caldesmon
What is the difference in how actins stain smooth muscle and myofibroblastic tumors?
Myofibroblastic tumors show a “tram track” pattern of staining with actins due to peripheral cytoplasmic accentuation (ie in nodular fasciitis) but in smooth muscle tumors the staining will be diffuse
What stains are positive in desmoplastic small round blue cell tumor and what translocation is present?
Polyphenotypic marker expression: WT1+, CK+, EMA+, desmin (dot-like), actin-, NSE+, syn/chr-, CD99 variable
t(11;22)(p13;q11.2 or q12): WT1-EWS
What is the molecular event in alveolar soft parts sarcoma?
t(X;17)(p11;q25) TFE3-ASPL fusion
What is the molecular event in aneursymal bone cyst?
t(16;17)q22;p13) CDH11-USP6 fusion
What are the molecular events in angiomatoid fibrous histocytoma?
*they are the same as for clear cell sarcoma
t(12;22)(q13;q12) EWSR1-ATF1 fusion
t(2;22)(q33;q12) EWSR1-CREB1 fusion
What are the molecular events in extraskeletal myxoid chondrosarcoma?
t(9;22)(q22;q12) EWS-NR4A3 fusion
t(9;17)(q22;q11) TAF2N-NR4A3 fusion
t(9;15)(q22;q21) TCF12-NR4A3 fusion
What are the molecular events in clear cell sarcoma?
*they are the same as angiomatoid fibrous histiocytoma
t(12;22)(q13;q12) EWSR1-ATF1 fusion
t(2;22(q33;q12) EWSR1-CREB1 fusion
What is the molecular event in desmoplastic small round blue cell tumor?
t(11;22)(p13;q12) EWSR1-WT1 fusion
What is the molecular event in DFSP?
Ring form of chr 17 and 22 COL1A1-PDGFB fusion
t(17;22)(q21;q13) COL1A1-PDGFB fusion
What are the molecular events in Ewings sarcoma/PNET?
t(11;22)(q24;q12) EWSR1-FLI1 fusion
t(21;22)(q12;q12) EWSR1-ERG fusion
t(2;22)(q33;q12) EWSR1-FEV fusion
t(7;22)(p22;q12) EWSR1-ETV1 fusion
t(17;22)(q12;q12) EWSR1-E1AF fusion
inv(22)(q12q12) EWSR1-ZSG fusion
t(16;21)(p11;q22) FUS-ERG fusion
What are the molecular events in infantile fibrosarcoma?
t(12;15)(p13;q26) ETV6-NTRK3 fusion (also in mesoblastic nephroma)
Trisomies 8, 11, 17, and 20
What are the molecular events in inflammatory myofibroblastic tumor?
t(1;2)(q22;p23) TPM3-ALK fusion
t(2;19)(p23;p13) TPM4-ALK fusion
t(2;17)(p23;q23) CLTC-ALK fusion
t(2;2)(p23;q13) RANB2-ALK fusion
What is the molecular event in leiomyosarcoma?
Complex with frequent deletion of 1p
What are the molecular events in liposarcomas?
Well-differentiated: Ring form of chromosome 12 Amplification of MDM2, CDK4, and others
Myxoid/Round cell: t(12;16)(q13;p11) TLS-DDIT3 fusion
t(12;22)(q13;q12) EWSR1-DDIT3 fusion
Pleomorphic: Complex
What is the molecular event in low grade fibromyxoid sarcoma?
t(7;16)(q33;p11) FUS-CREB3L2 fusion
What is the molecular event in myxofibrosarcoma?
Ring form of chromosome 12
What is the molecular event in rhabdoid tumor?
Deletion of 22q INI1 inactivation
What are the molecular events in rhabdomyosarcomas?
Alveolar: t(2;13)(q35;q14) PAX3-FOXO1A fusion
t(1;13)(p36;q14), double minutes PAX7-FOXO1A fusion
t(2 ;2)(q35 ;p23) PAX3-NCOA1 fusion
PAX3-AFX fusion
*hint* they will try to trick you!!!!! If you see FKHR, it is the same thing as FOX01! So you may see PAX3-FKHR or PAX7-FKHR
Embryonal: Trisomies 2q, 8 and 20 Loss of heterozygosity at 11p15
What is the molecular event in solitary fibrous tumor?
Inversion chromosome 12 NAB2-STAT6
What are the molecular events in synovial sarcoma?
Monophasic: t(X;18)(p11;q11) SYT-SSX1, SYT-SSX2 or SYT-SSX4 fusion
Biphasic: t(X;18)(p11;q11) Predominantly SYT-SSX1 fusion
What three disorders have multiple enchondromas?
Ollier disease, Maffucci syndrome, and metachondromatosis
*both of the first two have mutation in PTH1R on 3p21-22
Maffucci: sporadic disease characterized by the presence of multiple enchondromas associated with multiple hemangiomas. Also lymphangiomas may be apparent. Is associated with a higher risk of CNS, pancreatic, and ovarian malignancies.
Ollier: more common than Maffucci syndrome and is a non-hereditary disorder, and presents with multiple enchondromas often in a unilateral distribution (ie half the body of limb). However, hemangiomas and lymphangiomas are not seen in Ollier disease
What are the main benign and malignant polyostotic lesions of the bone?
Benign: Langerhans cell histiocytosis
Fibrous dysplasia
Paget disease
Angiomatous lesions
Malignant: mets, myeloma
How Does Osteoporosis Affect the Levels of Serum Calcium, Phosphate and PTH?
In spite of the marked decrease in mineral content in bone, serum calcium, phosphate and PTH are normal
Since there is no increase in osteoblastic activity, serum alkaline phosphatase is normal
*this is in contrast to osteomalacia where overactive resorption of bone results in increased calcium levels, decreased phosphorous
What tumor causes tumor associated osteomalacia (hint it looks like a solitary fibrous tumors with calcifications)?
Phosphaturic mesenchymal tumor
Present with weakness, bone pain, fracture
After you remove thier tumor, osteomalacia goes away
Micro description:
- Hypocellular tumor of bland spindled cells with small nuclei, indistinct nucleoli, osteoclast-like giant cells, myxoid change, hemangiopericytoma-like vessels, distinctive “grungy” calcified matrix, fat, microcysts, hemorrhage, incomplete rim of membranous ossification, metaplastic bone
- Infiltrative
- No/rare mitotic activity, no atypia
- Malignant: rare cases with nuclear atypia, 5+ mitotic figures/10 HPF, high cellularity, resembles MFH
What is the defect and mutation in osteogenesis imperfecta?
Defect in synthesis of collagen type I (COL1A1 and COL1A2) by osteoblast, fibroblast, and other cell types.
BQ! What disease is from osteoclastic failure and is a result of sclerosis of the bone with thickening of the cortex and filling of marrow cavity, “Erylenmeyer Flask”? What is another name for this disease they could use on boards?
Osteopetrosis aka Albers-Schonberg Disease
Associated anemia, extramedullary hematopoiesis, hypersplenism, and infection. Bones are brittle and fracture. Bone is dense and trabeculae have cores of cartilage. While there may be abundant osteoclasts, they are not functional and fail to resorb calcified cartilage.
What three histologic features are characteristic of chronic osteomyelitis? What chronic osteomyelitis disorder is seen in kids?
1) marrow fibosis, 2) plasma cells, 3) bony remodeling
CRMO= Chronic Recurrent Multifocal Osteomyelitis
*same findings histologically but it is in kids and they never culture out an organism and keeps coming back
What is the most common cause of this lesion?
Steroids
this is showing avascular necrosis
also DM, ETOH, Sickle cell dz and other hemoglobinopathies, deep sea divers and rarely Gaucher’s
*these are causes of idiopathic cases and tend to be bilateral and there is also the post-traumatic type which is usually unilateral
What is the characteristic feature shown indicative of?
AVASCULAR NECROSIS
This is showing “cresecent sign” where dead bone is pulling away from cortex and there is a space
COULD SHOW ON BOARD!
What is this a picture of?
Osteosarcoma arising in Paget disease!
1% of patients with Paget disease will develop osteosarcoma
You can tell this is arising in Paget because of the mosaic lines (changing direction) in the bone
What syndromes have multiple enchondromatosis?
Ollier disease (multiple enchondromas only)
Maffucci syndrome (multiple enchondromas with spindle cell hemangioendothelioma)
Patients in both are at increased risk for developing chondrosarcoma
What lesion is shown here (medullary and cortical continuity with underlying bone and hyaline cartilage cap <3cm)?
What hereditary disorder has multiple of these?
Osteochondroma
Multiple: Hereditary Multiple Exostoses (HME)
What is the main bone lesion that occurs in the epiphysis and therefore you should think about choosing on boards if given an epiphyseal tumor?
Chondroblastoma
Three components: chicken wire calcifications (buzz word), primitive chondroid cells, osteoclast-like giant cells
90% between 5-25yrs
BEWARE!! – low/intermediate T2W (95%) (meaning it has worrisome imaging findings but it is benign)
They have local recurrence 5%-10%
“Benign” metastases to soft tissue and lung
What is the typical question stem you will get for osteoid osteoma?
Less than 1 cm
PAIN AT NIGHT, RELIEVED by aspirin (because the tumor produces prostaglandins)
Radiolucent nidus with radiodense surrounding area (looks like a target)
Patients with hereditary retinoblastomas have several hundred fold greater risk of subsequently developing what tumor?
Osteosarcomas due to Rb gene mutation
What kind of osteosarcoma has a MDM2 mutation?
Parosteal osteosarcoma
What two syndromes have polyostotic fibrous dysplasia?
McCune Albright (endocrine and pigmented skin lesions)
Mazabraud syndrome (intramuscular myxoma usually overlying fibrous dysplasia)
What is the mutation in fibrous dysplasia?
*histology shows irregular spicules of woven bone WITHOUT osteoblastic rimming in a background of bland spindle cells (so called “Chinese letters”)
Activating mutations in GNAS1 gene of the alpha subunit of stimulatory G protein (Gsalpha)