Pathology

Noninvasive imaging can reliably diagnose some soft-tissue lesions such as lipomas, benign vascular tumors, and fibromatosis. For most other tumors, histologic examination of a biopsy specimen is currently the only reliable technique that can lead to a definitive diagnosis. Several techniques are in common use: fine-needle aspiration (FNA), core needle biopsy, incisional biopsy and excisional biopsy. FNA is the easiest to perform and can be safely undertaken at the first clinic visit of a patient presenting with an accessible mass that is clinically non-pulsatile. Although the tissue obtained is almost invariably inadequate for identification of tumor grade, its usefulness lies in its being able to identify other more common tumors like squamous cell carcinoma, thereby guiding further evaluation. Core needle biopsy, on the other hand, provides good tissue for diagnosis and grade can be determined in virtually all specimens.9 Lesions of the paranasal sinuses and nasal cavity may be visualized using modern endo-scopic techniques but obtaining a representative biopsy specimen from these tumors may be difficult.

Excisional biopsy of a suspected malignant mass should be avoided because foci of tumor have been

Table 17-2. SOME EXAMPLES OF TUMOR-SPECIFIC GENETIC ABNORMALITIES THAT HAVE BEEN IDENTIFIED

IN SOFT TISSUE SARCOMA

Histologic Diagnosis

Genetic Abnormality

Gene Fusion Product

Synovial sarcoma Ewing's sarcoma / Primitive neuroectodermal tumor Desmoplastic small round cell tumor Liposarcoma Dermatofibrosarcoma Myxoid chondrosarcoma Alveolar rhabdomyosarcoma t(x;18) (p11;q11) t(11,22) (q24;q12) t(21,22) (q12;q22) t(7,22) (p22;q12) t(11,22) (q13;q12)

t(12;16) (q13;p11) t(17,22) (q22;q13) t(9,22) (q31;q12) t(2,13) (q35-37;q14) t(1,13) (p36;q14)

SYT-SSX

EWS-FL11

EWS-ERG

EWS-ETV1

EWS-WT1

CHOP-TLS

PDGFB-COL1A1

EWS-TEC

PAX3-FKHR

PAX7-FKHR

shown to persist in the patient after such a proce-dure.10 Instead, an incisional biopsy allows for adequate sampling of viable tumor tissue under direct vision and ensures optimal hemostasis. The incision is planned directly over a point where the tumor feels closest to the skin and is oriented to allow its excision if a subsequent definitive procedure becomes necessary. Careful dissection should minimize opening up tissue planes and a sufficient wedge of viable, non-necrotic tissue must be sampled to be sent to the pathology laboratory in containers suitable for appropriate studies. If wound drainage is required after meticulous hemostasis, drains should exit either through or very close to the incision. Frozen-section analysis of the biopsy specimen can be used to confirm that diagnostic tissue has been sampled, but otherwise its role in establishing accurate histologic diagnosis is limited.

A positive smear from an FNA of osteogenic sarcoma and other bony sarcomas has been reported to be very reliable, but open biopsy is mandatory for negative or indeterminate smears.11 The extra-osseous soft-tissue component of a bony lesion may be adequately biopsied using a core biopsy needle such as the Jamshidi needle. Open biopsy of bone lesions is generally not recommended for craniofa-cial tumors as it contaminates tissue planes and may ultimately increase the extent of definitive resection.

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