The Milan System For Reporting Salivary Gland CytopathologyEdit

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is a structured framework designed to standardize how cytology samples from salivary glands are interpreted and communicated. By providing clear terminology, a rationale for management, and an estimated risk of malignancy associated with each category, the system aims to reduce ambiguity in the pathologist’s report and align expectations among surgeons, radiologists, and oncologists. Since its introduction, it has been adopted widely in various healthcare settings and has become a reference point for multidisciplinary decision-making in cases involving salivary gland lesions. The MSRSGC fits into a broader family of organ-specific reporting schemes that seek to improve patient outcomes through consistency, evidence-based guidance, and defensible clinical pathways. It is often invoked in conjunction with complementary imaging and clinical assessment to guide biopsies, surgical planning, and surveillance.

Overview of the MSRSGC

The MSRSGC defines six diagnostic categories (commonly referred to as I–VI or C1–C6) that cover the spectrum of salivary gland cytology findings. Each category includes a concise description of its cytologic criteria, an estimated risk of malignancy (ROM) with the intent of guiding clinical management, and recommended next steps. The categories and their general intent are:

Category I: Non-diagnostic

What it means: The sample is unsatisfactory for evaluation due to scant cellularity, poor preservation, or technical issues.
Typical features: Insufficient cellular material to make a meaningful assessment.
ROM and management: ROM is variable depending on prior sampling and context; often requires repeat fine-needle aspiration (FNA) with optimized technique and possibly adjunct imaging.
Clinical approach: Re-aspiration with attention to obtaining representative material; consider ultrasound guidance and correlation with imaging.

Category II: Non-neoplastic

What it means: The lesion represents a non-neoplastic process or inflammatory/reactive change rather than a true neoplasm.
Typical features: Inflammatory cells, debris, ductal or inflammatory changes without definite neoplastic epithelial populations.
ROM and management: ROM is generally low; management targets the underlying inflammatory or infectious process and observation as appropriate.
Clinical approach: Treat infectious or inflammatory etiologies; imaging and follow-up as indicated.

Category III: Atypia of undetermined significance (AUS)

What it means: Atypical features are present that are insufficient to classify as benign neoplasm, malignant neoplasm, or another category with confidence.
Typical features: Some cellular atypia or architectural concerns, but not definitive for a neoplastic process or malignancy.
ROM and management: ROM is intermediate and context-dependent; often prompts repeat FNA with additional sampling or adjunct studies.
Clinical approach: Combine repeat aspiration, targeted imaging, and, when indicated, core needle biopsy or excisional biopsy for definitive characterization.

Category IV: Benign neoplasm

What it means: A benign salivary gland neoplasm is favored.
Typical features: Epithelial and myoepithelial components arranged in patterns consistent with benign tumors (for example, pleomorphic adenoma) or other non-cancerous neoplasms.
ROM and management: ROM is low for benign neoplasms but not zero; management typically involves surgical excision tailored to the lesion’s location and patient factors.
Clinical approach: Plan surgery when indicated by size, symptoms, or diagnostic confidence; correlate with imaging.

Category V: Salivary gland neoplasm of uncertain malignant potential (SUMP)

What it means: A neoplasm is identified, but its malignant potential cannot be determined reliably from cytology alone.
Typical features: Neoplastic cells present but without definitive cytologic features distinguishing benign from malignant behavior.
ROM and management: ROM is higher than in benign categories; management often involves definitive histologic assessment via surgical excision with careful planning.
Clinical approach: Discuss surgical options and obtain histopathology to establish malignant potential; use imaging to guide the extent of resection.

Category VI: Malignant

What it means: Features strongly favor a malignant salivary gland neoplasm.
Typical features: Cytologic evidence of malignancy, such as high-grade epithelial cells, invasive patterns, or characteristic cytomorphology of known malignant entities.
ROM and management: ROM is high; management typically requires oncologic planning, which may include broader surgical resection, neck evaluation, and adjuvant therapy as indicated.
Clinical approach: Coordinate with otolaryngology/head-and-neck oncology and radiology to determine the best multidisciplinary treatment plan.

In addition to category definitions, the MSRSGC emphasizes the intended use of cytology as a triage tool—helping clinicians decide when imaging, repeat sampling, or surgical intervention is warranted. The system also integrates with clinical context and imaging findings to improve diagnostic confidence and patient safety. For terminology and interpretation in broader cytopathology discussions, references to related concepts such as Cytopathology and Fine-needle aspiration are common, and the framework often appears alongside guidance from other professional bodies and literature on salivary gland lesions.

Diagnostic accuracy, limitations, and practice implications

The MSRSGC is designed to improve communication and standardize decisions across institutions. By assigning a ROM to each category, it supports evidence-based referrals for surgery, imaging, or surveillance, and it provides a framework for consistent documentation and medico-legal defensibility. However, the system is not a substitute for clinical judgment. Salivary gland cytology can be subject to sampling limitations, cystic changes, and overlap between benign and malignant entities, which means some cases will require additional tissue for an accurate diagnosis. Cross-sectional imaging and correlation with clinical features—such as lesion size, growth rate, facial nerve involvement, and the patient’s overall risk profile—remain integral to patient management.

Adoption of the MSRSGC has prompted further research and refinement. Validation studies across institutions and regions help calibrate ROM estimates and reinforce the most appropriate management strategies for each category. In practice, the system supports a disciplined approach to decision-making and helps reduce unnecessary surgeries when conventional wisdom would have allowed for observation or repeat sampling instead.

Controversies and debates

As with any standardized framework, there are ongoing discussions about how best to apply the Milan categories in diverse clinical settings. Key points of debate include:

Interpretation of AUS and SUMP: Critics argue that AUS and SUMP can lead to variable decisions, with some clinicians pushing for repeat sampling or more aggressive intervention. Proponents maintain that these categories prevent premature labeling of a lesion and encourage additional data to avoid misclassification.
Balancing overdiagnosis and underdiagnosis: Some observers worry that the system might contribute to overuse of procedures in ambiguous cases, while others emphasize that standardization reduces variability, which in turn supports safer, more predictable patient care and outcomes.
Medico-legal considerations: By laying out explicit categories and management recommendations, the MSRSGC can help clarify responsibility and reduce uncertainty in difficult cases. Critics may worry about rigid frameworks, but advocates argue that clear guidelines reduce the likelihood of inconsistent or biased interpretations and improve accountability.
Access and equity: Proponents stress that standardized reporting can improve consistency across providers and institutions, potentially narrowing gaps in care. Critics sometimes argue that implementing such systems requires resources and training that may be unevenly distributed; nonetheless, the long-term aim is more efficient care pathways and better use of imaging and surgical services.
Reactions to critiques from broader policy perspectives: When arguments arise that emphasize patient autonomy or cost containment, supporters of standardized cytology reporting counter that structured frameworks actually enhance patient safety and informed consent by making risks explicit and decisions traceable. In practice, the focus remains on delivering precise, evidence-based guidance while avoiding unnecessary interventions.

History and adoption

The Milan System for Reporting Salivary Gland Cytopathology emerged from collaborations among pathologists and clinicians seeking a common language for interpreting salivary gland FNA samples. Its development drew on experiences with prior cytology reporting schemes and was designed to be adaptable to a range of practice environments, from high-volume academic centers to community clinics. Since its introduction, the MSRSGC has been described in numerous institutional experiences and reviews, and it continues to influence how otolaryngologists, radiologists, and pathologists coordinate care for patients with salivary gland disease. For readers exploring related frameworks, see Milan System for Reporting Salivary Gland Cytopathology and connections to broader cytopathology standards such as Bethesda System references in adjacent organ systems.