Anatomic pathology (AP) is the diagnostic discipline that examines tissue and cells removed from the body — from a needle biopsy to a whole organ — and renders the diagnoses that drive cancer treatment, surgical decisions, and definitive disease classification. Its physical home in a hospital is a chain of specialized rooms: specimen accessioning, gross dissection ("grossing"), the histology laboratory, cytology, immunohistochemistry and molecular bench space, the pathologist sign-out suite, and — frequently co-located for logistical and code reasons — the autopsy suite and morgue. These spaces are united by one design challenge above all others: the handling of fixatives and processing solvents, principally formaldehyde and xylene, which dominate the ventilation, plumbing, fire-protection, and waste design of the entire AP footprint.

Scope and where this article sits

This article covers the anatomic-pathology surgical-pathology workflow (grossing, histology, special stains/IHC, cytology, molecular AP), the pathologist work environment, and the autopsy/morgue suite, including their distinctive chemical-handling, ventilation, refrigeration, and decedent-logistics requirements. It does not cover the automated clinical core lab (chemistry/hematology bench and automation lines), microbiology biosafety containment, the blood bank/transfusion service, or front-end phlebotomy and specimen receiving for the clinical lab — those are addressed by adjacent articles in this Part. Where AP shares back-of-house with the core lab (loading dock, soiled/clean utility, shared chemical storage), the shared elements are noted here from the AP perspective.

The anatomic-pathology workflow and the rooms it requires

AP is best understood as a one-directional specimen journey, and the room program follows that journey. Designing the suite around the workflow — rather than as a set of generic lab rooms — is what prevents cross-contamination, specimen mix-ups, and bottlenecks.

A clean directional flow — fresh/unfixed specimens segregated from fixed, dirty grossing separated from clean histology output, and a logical progression from accessioning to sign-out — is the organizing principle. Frozen-section service is a special case: it must deliver an answer to the surgeon in minutes, so it is either embedded near the operating-room suite or tightly linked to it by a dedicated pneumatic tube, runner route, or telepathology connection.

Formaldehyde and xylene: the chemicals that define the design

Two chemicals set the environmental envelope for nearly every AP space.

• Formaldehyde (formalin) is the universal tissue fixative. It is a known human carcinogen and a respiratory/eye irritant. OSHA regulates it under a specific substance standard (29 CFR 1910.1048) with a permissible exposure limit (PEL) of 0.75 ppm as an 8-hour time-weighted average, a short-term exposure limit (STEL) of 2 ppm, and an action level of 0.5 ppm that triggers exposure monitoring. Grossing — where large fixed specimens are opened and dissected — is the highest-exposure activity in the building and drives the most aggressive local exhaust design.
• Xylene (and graded alcohols) are the clearing/dehydrating solvents used in tissue processors, stainers, and coverslippers. Xylene is flammable and a CNS/respiratory irritant, which couples the histology room to both ventilation and flammable-liquid fire-code requirements.

Because of these two agents, the AP suite is treated as a laboratory work area under NFPA 45 (Fire Protection for Laboratories Using Chemicals), ventilation follows ASHRAE Standard 170 and the FGI Guidelines for Design and Construction of Hospital and Outpatient Facilities, and the rooms carry elevated air-change rates, directional pressurization, and local exhaust capture far beyond a general office or clean lab.

Grossing room — the highest-exposure space in the building

The grossing room is where formaldehyde control is won or lost. Design intent is to capture formaldehyde vapor at the point of generation before it reaches the breathing zone.

• Grossing/dissection stations are purpose-built fixtures with integral downdraft and/or backdraft (rear-slot) exhaust, a perforated work surface, a built-in sink and disposal, a formalin dispense/recapture system, a cutting board, lighting, and a camera/dictation mount. Each station is a dedicated exhaust point — these are exhaust-intensive fixtures, not casework with a hood bolted on.
• Ventilation is 100% outside air, exhausted directly to the exterior with no recirculation; the room is held at negative pressure relative to surrounding spaces so vapor migrates inward. Air-change rates are high (a common engineering target is on the order of 10–15+ air changes per hour, with the grossing stations themselves providing high face-capture velocities); the controlling design metric is keeping measured formaldehyde below the OSHA action level at the worker's breathing zone, verified by industrial-hygiene monitoring, not the ACH figure alone.
• Make-up air must be engineered to balance the large exhaust volume without creating drafts that pull vapor across the operator; low-velocity, well-distributed supply is essential.
• Specimen photography, a large-format dictation/voice-capture interface, and a specimen radiography capability (a cabinet specimen X-ray for breast and bone cases) are frequently included; the specimen-radiography cabinet is a registered radiation-producing device requiring shielding sign-off and state/AHJ registration.
• Bulk/large-specimen storage (wet tissue and "stock jars" held in formalin for the retention period mandated by CAP) is a vented, often refrigerated, formalin-saturated environment that needs its own exhaust and flammable/chemical-storage treatment.
• Eyewash and emergency safety: plumbed eyewash (and a safety shower where bulk formalin is handled) per ANSI/ISEA Z358.1, spill kits, and PPE storage are mandatory.