The journey of a tissue specimen from the operating room to the pathologist’s microscope begins with reception in the histopathology laboratory and systematic gross examination. Every subsequent step — processing, sectioning, and staining — depends on correct identification, handling, and sampling at this stage.
Specimen Reception and Accessioning
Upon arrival, the specimen is checked against the accompanying request form. Three identifiers are verified: patient name, date of birth, and medical record number. The specimen container is examined for correct labeling and leakage. The number of containers and their contents are reconciled with the form. Discrepancies are immediately reported to the submitting clinician.
Each specimen is assigned a unique accession number — typically a year-prefixed sequential number (e.g., S26-12345 for surgical pathology, 2026, case 12345). Multiple specimens from the same patient during the same encounter receive distinct accession numbers but may be linked. Barcode labels are printed and affixed to the requisition, specimen container, and all subsequent documents and cassettes.
Orientation and Inking
Proper orientation is critical. Small biopsies are often pre-oriented by the surgeon on filter paper or in a cassette. Large specimens require the pathologist or assistant to identify anatomical landmarks — serosal surfaces, mucosal surfaces, resection margins, and lymph node-bearing areas.
Inking applies colored dyes (India black, blue, green, yellow, orange, red) to specific resection margins. The colors persist through processing and staining, allowing the pathologist to identify margins microscopically. A common scheme: proximal margin (black), distal margin (blue), radial/circumferential margin (green), and deep margin (yellow). The inked surface is touched gently to absorbent paper to dry before formalin immersion. Multiple colors require sequential application with drying between to prevent mixing.
Gross Description
The gross description follows a standardized format: organ/tissue type, laterality (right, left, midline), specimen type (biopsy, excision, resection), dimensions in three axes (length × width × thickness in cm), weight (for organs, in grams), external surface (color, consistency, lesions), cut surface (color, texture, necrosis, hemorrhage, cystic changes), and margins (distance of tumor from each inked margin). Photographs document gross findings for the report, tumor board presentation, and medicolegal purposes.
Sampling and Cassette Submission
Representative sections are taken for processing. General principles include: one section per cm of tumor diameter for large tumors; sections demonstrating the relationship between tumor, normal tissue, and margins; sections of all grossly visible lesions; sections of lymph nodes; and sections of grossly unremarkable tissue for comparison.
Sections are cut at 2-4 mm thickness — thin enough for complete fixation and processing but thick enough to maintain architectural integrity. Each section is placed in a labeled tissue cassette (perforated plastic container) that carries the accession number, block letter (A, B, C, etc.), and a brief description (e.g., “tumor,” “margin-proximal,” “lymph node”).
Specimen Type-Specific Protocols
Breast specimens — core needle biopsies are counted and wrapped in lens paper; excisions (lumpectomy, mastectomy) are inked, sectioned at 5 mm intervals, and radiographed for mammographic correlation or specimen radiography for margin assessment.
Colorectal resections — opened along the anti-mesenteric border, pinned to a corkboard, fixed overnight before sectioning. The tumor is sectioned through its maximum dimension. Lymph nodes are dissected from the mesentery (minimum 12 nodes for cancer staging).
Prostate specimens — radical prostatectomies are inked (right side blue, left side black), weighed, measured, and sectioned at 3-4 mm intervals from apex to base. The entire gland is submitted (whole-mount or standard sections) for accurate Gleason grading and staging.
Skin specimens — orientation is marked with sutures (short suture = superior, long suture = lateral). Margins are inked. Elliptical excisions are bread-loafed at 2-3 mm intervals; shave and punch biopsies are bisected.
Safety
Gross examination is performed in a ventilated grossing station with downdraft airflow that captures formalin fumes. Personal protective equipment includes fluid-resistant gown, cut-resistant gloves (for bone and calcified specimens), face shield, and respirator when handling known infectious specimens. All instruments and surfaces are decontaminated between cases. Sharp waste (scalpel blades, needles) is disposed in designated sharps containers.
