Soft tissue Flashcards
Subcutaneous lesion with palisading granulomas surrounding areas of fibrinoid necrosis
Rheumatoid nodule
Differential diagnosis
Granuloma annulare (if increased dermal mucin)
Epithelioid sarcoma
Plan:
Correlate with clinical history and dermatologic impression (?rheumatoid arthritis ?elevated RF)
IPX to support Dx: CD68
IPX to discount DDx: Pancytokeratin, INI1 (epithelioid sarcoma would stain with cytokeratin and INI1 would be lost)
Soft tissue lesion with spindle cells in tissue culture, fascicular, or storiform arrangement, in myxoid to collagenous background, with lymphocytes and extravasated red blood cells. Nuclei are ovoid with indistinct nucleoli, but may have frequent mitoses.
Nodular fasciitis
Differential diagnosis:
Fibromatosis
Low grade fibromyxoid sarcoma
Inflammatory myofibroblastic tumour
DF, DFSP (near skin)
Plan:
Correlate with clinical history and radiology (?rapid growth)
Examine further sections (e.g. for total size, relation to margins, areas of differing morphology)
IPX to support Dx: SMA and desmin (expect patchy SMA positivity, negative for desmin).
IPX to discount DDx: Beta catenin, MUC4, ALK1, CD34
Molecular: FISH for USP6 rearrangement
Well circumscribed tumour with branching blood vessels (may be hyalinised) surrounded by collars of uniform small round cells with indistinct borders (syncytial growth) eosinophilic cytoplasm and central very bland round nuclei
Glomus tumour
Differential diagnosis:
Myopericytoma
Angioleiomyoma
Plan:
Correlate with clinical history and radiology (?subungual lesion)
IPX to support Dx: SMA (expect positive)
IPX to discount DDx: Desmin
No further specific action required for this benign diagnosis
Encapsulated tumour with alternating hypercellular areas (Antoni A) and hypocellular areas (Antoni B). Hypercellular areas contain clusters of parallel palisading nuclei (‘Verocay bodies’). Nuclei are euchromatic and fusiform. Vessels are thick-walled and hyalinized.
Schwannoma
Differential diagnosis:
Leiomyoma
Plan:
Correlate with clinical history and radiology
IPX to support Dx: S100 (expect strong diffuse staining)
IPX to discount DDx: SMA, desmin
Advice to clinician: May be sporadic or assiociated with familial syndromes (e.g. neurofibromatosis type 2, schwannomatosis). Clinical correlation is required
Skin tumour with dense storiform architecture of monomorphic spindle cells in dermis with growth into subcutis along fibrous septa (honeycomb pattern). No associated epidermal hyperplasia
Dermatofibrosarcoma protuberans
Differential diagnosis:
Cellular dermatofibroma
Nodular fasciitis
Solitary fibrous tumour
Plan:
Correlate with clinical history and radiology
Examine further sections (e.g. for size, relation to margins, fibrosarcomatous transformation)
IPX to support Dx: CD34 (expect diffuse positivity)
IPX to discount DDx: Factor XIIIa, STAT6
Next steps: Synoptic report, discuss at MDT
Well circumscribed tumour of adipocytes admixed with cells with multivacuolated, granular cytoplasm with small central nucleus.
Hibernoma
Plan:
Correlate with clinical history and radiology
Examine further blocks
IPX to support Dx: Not required
No specific further action required for this benign diagnosis
Fat cells admixed with bland spindle cells and ropey collagen with scattered mast cells. Pleomorphic variant has bizarre giant cells and ‘floret’ cells with hyperchromatic wreath shaped nuclei.
Spindle cell / pleomorphic lipoma
Differential diagnosis:
Fibrolipoma
Well differented liposarcoma / atypical lipomatous tumour
Plan:
Correlate with clinical history and radiology (?back/neck location)
Examine further blocks (e.g for size, relation to margins, areas of differing morphology)
IPX to support Dx: CD34, RB1 (expect CD34 positivity with loss of RB1)
IPX to discount DDx: MDM2
No specific action required for this benign diagnosis
Myxoid tumour with small regular rounded cells and delicate branching ‘chicken wire’ capillary network. May have areas of fat or lipoblasts.
Myxoid liposarcoma
Differential diagnosis:
Myxofibrosarcoma
Extraskeletal myxoid chondrosarcoma
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for size, relation to margins, percentage of round cell component)
Molecular to support Dx: FUS::DDIT3 rearrangement
Molecular to discount DDx: EWSR1::NR4A3 rearrangement
Next steps: Synoptic report, discuss at MDT
Adipose tissue with variably sized adipocytes and increase in fibrous interstitium, containing lipoblasts and atypical cells with hyperchromatic irregular nuclei.
Well differentiated liposarcoma / atypical lipomatous tumour
Differential diagnosis:
Benign lipoma
Spindle cell / pleomorphic lipoma
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for size, margins, areas of differing morphology or dedifferentiation)
IPX to support Dx: MDM2, CKD4 (expect positive)
IPX to discount DDx: CD34, Rb
Molecular: FISH for MDM2 amplification
Next steps: Synoptic report, discuss at MDT
Nearly acellular lesion of mucin within muscle, with rare small stellate cells without atypia, and very few capillaries
Intramuscular myxoma
Differential diagnosis:
Myxoid liposarcoma
Myxofibrosarcoma
Extraskeletal myxoid chondrosarcoma
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for size, relation to margins, areas of differing morphology)
Molecular to support Dx: GNAS1 point mutation
Molecular to discount DDx: FUS::DDIT3, EWSR1::NR4A3 rearrangement
No specific further action required for this benign diagnosis
Unencapsulated proliferation of bland spindle cells with thin, wavy ‘serpentine’ nuclei. Stroma is myxoid or shows ‘shredded carrot’ collagen bundles and contains admixed mast cells.
Neurofibroma
Plan:
Correlate with clinical history and radiology
IPX to support Dx: Not required for diagnosis
Advice to clinician: May be sporadic or associated with neurofibromatosis type 1. Clinical correlation is required
Soft tissue lesion with multple tortuous bundles of bland spindle cells with thin, wavy ‘serpentine’ nuclei. Stroma is myxoid or shows ‘shredded carrot’ collagen bundles and contains admixed mast cells
Plexiform neurofibroma
Plan:
Correlate with clinical history and radiology (?patient with NF1)
Examine further blocks (e.g. for malignant transformation)
IPX to support Dx: Not required for diagnosis
Advice to clinician: This type of neurofibroma is quite strongly associated with neurofibromatosis type 1. Clinical correlation is required
A soft tissue tumour containing a mixture of mature fat and fibrous tissue with densely eosinophilic globular elastic fibres
Elastofibroma
Plan:
Correlate with clinical history (?scapular region mass)
Examine further blocks (e.g. for size, relation to margins)
Special stains: Elastin (highlight abnormal elastic fibres)
No specific action required for this benign diagnosis
Unencapsulated lesion composed of variable sized, closely packed nerve bundles along with dense collagen in the background.
Traumatic neuroma
Plan:
Correlate with clinical history and radiology (?painful lesion ?prior trauma)
IPX to support Dx: Not required for diagnosis
No specific further action required for this benign diagnosis
‘Patternless pattern’ of spindled cells in pink collagenous stroma. Architectural ‘cracks’ are common. Vessels are ‘staghorn,’ gaping and branching vessels without an appreciable wall thickness - the tumor appears to extend right up to the endothelium.
Solitary fibrous tumour
Differential diagnosis:
Synovial sarcoma
Myopericytoma
GIST
DFSP
Plan:
Correlate with clinical history and radiology (?arising from serosal surface)
Examine further blocks (e.g. for size, relation to margins, areas of differing morphology)
IPX to support Dx: CD34, STAT6 (expect positive)
IPX to discount DDx: TLE1, SMA, CD117 and DOG1
Next steps: Synoptic report, discuss at MDT
Highly malignant appearing soft tissue tumour with marked pleomorphism, large dark nuclei with bizarre shapes, multinucleated tumour cells, and frequent mitoses. Dark, dense, granular chromatin.
Undifferentiated pleomorphic sarcoma
Differential diagnosis:
Pleomorphic leiomyosarcoma
Pleomorphic rhabdomyosarcoma
De-differentiated liposarcoma
High grade MPNST
Sarcomatoid carcinoma
Melanoma
Anaplastic large cell lymphoma
Plan:
Correlate with clinical history and radiology
Examine further blocks (extensively sample lesion, for areas of differing morphology that may offer a specific diagnosis)
IPX to support Dx: No specific marker available
IPX to discount DDx: SMA, desmin, myogenin, myoD1, H3K27me3, AE1/AE3, S100 SOX10 MelanA, CD45
Molecular: FISH for MDM2 amplification
Next steps: Synoptic report, discuss at MDT
Well circumscribed proliferation of capillary sized vessels around a central vessel, lined by epithelioid endothelial cells. Abundant stromal eosinophilic and lymphocytic inflammatory infiltrate.
Epithelioid Haemangioma
Plan:
Correlate with clinical history and radiology (?head/neck or distal extremity location)
IPX to support Dx: CD31, CD34, ERG
No further specific action required for this benign diagnosis
Dermal and subcutaneous multinodular lesion with aggregates of chronic inflammatory cells at the periphery. The nodules contain central necrosis and haemorrhage imparting a granulomatous appearance at low power. Composed of epithelioid cells with mildly atypical nuclei
Epithelioid sarcoma
Differential diagnosis:
Rheumatoid nodule
Granuloma annulare
Rule out melanoma
Plan:
Correlate with clinical history and radiology (?distal extremity location)
IPX to support Dx: AE1/AE3, INI1 (expect positive to cytokeratin, INI lost)
IPX to discount DDx: CD68, S100 and SOX10 and Melan A
Next steps: Synoptic report, discuss at MDT
