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


