Built for the pathologist who has to move from a core biopsy fragment to a confident, actionable diagnosis before the tumor board convenes, this reference grounds soft tissue tumor pathology in the correlation of morphology, immunohistochemistry, and molecular and cytogenetic signature — fusion genes, gene amplifications, loss-of-expression markers — rather than pattern recognition alone. It moves from foundational diagnostic method (triage, biopsy planning, panel construction, molecular test selection, FNCLCC grading) through every major tumor lineage — adipocytic, fibroblastic, vascular, muscle, nerve sheath, and molecularly defined sarcoma families — into the special clinical contexts and multidisciplinary decisions that follow a diagnosis into the clinic.

Every chapter builds its reasoning through the Diagnostic Signature System — Entity, Morphologic Signature, Immunomolecular Signature, Trap Logic, and Diagnostic Anchor — consolidated at the back into an indexed Atlas cross-referenced by molecular signature, anatomic compartment, and morphologic pattern.

From the Biopsy to the Final Diagnosis, You Will

• Triage a soft tissue mass correctly — clinical, radiologic, and biopsy-planning criteria that separate a probable sarcoma from a reassuring mimic before the first stain is ordered.
• Confirm dedifferentiated liposarcoma — MDM2/CDK4 amplification testing that distinguishes it from an unrelated high-grade sarcoma sampled without its lipomatous component.
• Separate desmoid fibromatosis from nodular fasciitis and low-grade fibrosarcoma — the fascicular pattern, vascularity, and beta-catenin result that resolves this recurring spindle cell triage.
• Resolve nerve sheath and molecularly defined sarcoma calls — H3K27me3 loss in MPNST, SS18-SSX in synovial sarcoma, SMARCB1 loss in epithelioid sarcoma, and the fusion panel separating Ewing, CIC-rearranged, and BCOR-rearranged round cell sarcoma.
• Clear a diagnosis of undifferentiated sarcoma — the documented exclusion panel that justifies the call rather than defaulting to it.
• Read pediatric vascular anomalies and reactive mimics — ISSVA-based vascular tumor versus malformation, and the mitotic pattern separating nodular fasciitis and myositis ossificans from true sarcoma.
• Call retroperitoneal disease with confidence — dedifferentiated liposarcoma and vena caval leiomyosarcoma worked through their defining molecular and anatomic signatures.
• Carry the diagnosis into management — margin adequacy, histology-directed systemic therapy selection, and surveillance imaging that tells recurrence from postsurgical change.

Put this reference beside the microscope — the reasoning every soft tissue diagnosis, and every patient it reaches, depends on.