Qap (Anatomical Pathology) 

QAP Peer Review

AP183
Case History: F/65 Right thigh mass
Intended diagnosis: Malignant fibrous histiocytoma. Contributed by:USK
Code Diagnosis Comment Score
anonymous High grade sarcoma (100%), differential diagnoses include malignant fibrous histiocytoma, pleomorphic liposarcoma etc. To sample more blocks to look for better differentiated areas and to perform immunostains including S100, actin, desmin, CD34 to determine the nature of the tumour.  100
anonymous High grade sarcoma (pleomorphic sarcoma) nil  100
anonymous Undifferentiated high grade pleomorphic sarcoma. DDx malignant melanoma, MPNST, sarcomas (osteosarcoma, leiomyosarcoma, liposarcoma and rhabdomyosarcoma). Additional sections to be examined. A panel of immunostains would include S-100 protein, muscle markers (desmin, actin, myogenin) and HMB45.  100
anonymous Malignant spindle cell tumor; please see comment Immunostaining for follicular dendritic cell markers (CD21/35); myoid markers (actin, desmin, for leiomyosarcoma); S100 for MPNST/ melanoma/ interdigitating dendritic cells sarcoma; Further sampling for areas of well-differentiated liposarcoma (for de-differentiated liposarcom) If no definite lineage demonstrated : malignant fibrous histiocytoma.  100
anonymous Undifferentiated malignant tumor consistent with malignant fibrous histiocytoma, pleomorphic-storiform subtype. 100% Immunostains to exclude possible line of differentiation eg. CK, S100, LCA, desmin, actin etc. There is some suggestion of dedifferentiation. Suggest extensive sampling to look for better differentiated areas.  100
anonymous High grade sarcoma (with malignant fibrous histiocytoma pattern) arising from low grade sarcoma. (100%) Sample more blocks for hints of differentation, e.g. lipoblasts for liposarcoma; striation for skeletal muscle; cartilage for chondroid; nerve sheath for malignant peripheral nerve sheath tumor. Do immunostains to help differentiating the primary lesion. Desmin & actin for smooth muscle; myogenin for skeletal muscle; S100 protein for nerve sheath; CD31 for endothelial; CD34 for others.  100
anonymous Right thigh mass - High grade pleomorphic sarcoma, MFH-like, with leiomyosarcoma area 100% Thorough sampling of tumor required. To correlate with immunostains results for actin, desmin and S100 protein. It is possibe that the MFH part arises from de-differentiation of lower grade part of leiomyosarcoma.  100
anonymous High grade sarcoma (100%) To examine more blocks to look for evidence of differentiation +/- dedifferentiated areas. Perform immunohistochemical studies for tumour typing : Smooth and skeletal muscle: SMA, Desmin, myoD1, myogenin Neural and lipomatous : S100 Epithelial: BCK  100
anonymous High grade sarcoma: Pleomorphic malignant fibrous histiocytoma VS Pleomorphic liposarcoma nil  100
anonymous Pleomorphic MALIGNANT FIBROUS HISTIOCYTOMA (100%) Immunohistochemical stains including pan-cytokeratin, S-100, muscle-specific actin, desmin, CD31, CD34 to rule out specific tumor differentiation.  100
anonymous Pleomorphic sarcoma 100% CD21/35 to exclude FDC sarcoma SMA/desmin for leiomyosarcoma S100 for MPNST  100
anonymous High grade pleomorphic sarcoma Possiblities include pleomorphic rhabdomyosarcoma, dedifferentiated liposarcoma, malignant peripheral nerve sheath tumor etc. Suggest taking more blocks, immunohistochemistry and electron microscopy to differentiate.  100
anonymous Undifferentiated sarcoma, consistent with pleomorphic MFH nil  100
anonymous Sarcoma with dedifferentiation. Do S100 protein for neurogenic sarcoma, do desmin, SMA, myo-D1 to exclude rhabdomyosarcoma, leiomyosarcoma. Do CD34. Probability: 100% nil  95
anonymous Pleomorphic sarcoma (100%), favour malignant fibrous histiocytoma (MFH) (95% probability), pleomorphic rhabdomyosarcoma (5%) Perform MyoD1 immunostain to exclude pleomorphic rhabdomyosarcoma  100
anonymous High grade sarcoma (100%), suggestive of malignant peripheral nerve sheath tumour Immunohistochemical for S-100 protein, SMA, desmin and myogenin.  95