How are ulcers classified in a patient, particularly considering factors such as etiology, location, and relevant medical history, including conditions like diabetes?

Classification of Ulcers

Ulcers should be classified based on three primary frameworks: anatomical location (oral vs. foot), etiology (traumatic, infectious, ischemic, neuropathic, autoimmune), and severity grading using validated systems—specifically SINBAD for diabetic foot ulcers and clinical descriptors for oral ulcers.

Fundamental Classification Principles

Etiological Classification

Ulcers are fundamentally divided by their underlying cause rather than simply by chronicity 1:

• Traumatic ulcers: Caused by mechanical (sharp edges), physical (thermal burns), or chemical (acid/alkali) factors 1
• Infectious ulcers: Bacterial, fungal, or viral origins 2, 3
• Vascular ulcers: Related to ischemia or venous insufficiency 1, 4
• Neuropathic ulcers: Secondary to loss of protective sensation 1, 5
• Autoimmune/systemic disease ulcers: Associated with conditions like pemphigus, lichen planus, inflammatory bowel disease 1, 3
• Neoplastic ulcers: Malignant transformation requiring urgent biopsy 1, 2

Anatomical Location Classification

Oral Ulcers are classified by mucosal location 2:

• Non-keratinized movable mucosa (buccal, labial, floor of mouth) suggests aphthous ulcers 2
• Keratinized mucosa involvement suggests other etiologies 1
• Stellate ulcers with undermined edges suggest tuberculosis 1

Diabetic Foot Ulcers are classified by anatomical site 1, 5:

• Forefoot locations (score 0 in SINBAD) 1
• Midfoot and hindfoot locations (score 1 in SINBAD) 1
• Plantar surface ulcers (43% of cases) versus toe ulcers (54% of cases) 6

Recommended Classification Systems by Clinical Context

For Diabetic Foot Ulcers: SINBAD System (First-Line)

The SINBAD classification should be used as the primary system for communication between healthcare professionals managing diabetic foot ulcers 1, 5. This system grades six parameters, each scored 0 or 1:

• Site: Forefoot (0) vs. midfoot/hindfoot (1) 1
• Ischemia: Palpable pulse present (0) vs. clinical evidence of reduced flow (1) 1
• Neuropathy: Protective sensation intact (0) vs. lost (1) 1
• Bacterial infection: Absent (0) vs. present (1) 1
• Area: <1 cm² (0) vs. ≥1 cm² (1) 1
• Depth: Confined to skin/subcutaneous tissue (0) vs. reaching muscle/tendon/deeper (1) 1

Critical implementation point: Individual clinical descriptors must be documented, not just the total score, as the score alone provides insufficient information for proper triage 1, 5.

The SINBAD system requires no specialist equipment beyond clinical examination, making it feasible in resource-limited settings where most diabetic foot ulcers occur 1. It has been validated in 12 studies with substantial to good reliability 1, 5.

For Infected Diabetic Foot Ulcers: IDSA/IWGDF Classification

For characterizing infected foot ulcers, use the IDSA/IWGDF classification system 1, 5:

• Grade 1: Uninfected 5
• Grade 2: Mild infection 5
• Grade 3: Moderate infection 5
• Grade 4: Severe infection with systemic inflammatory response 5

Alternative System When Vascular Expertise Available: WIfI

Consider the WIfI system (Wound, Ischemia, foot Infection) when peripheral artery disease is suspected or confirmed and when vascular surgery resources and expertise are available 1, 5. This system provides superior stratification of healing likelihood and amputation risk in ischemic ulcers 1.

Systems to Avoid

The Wagner classification should NOT be used as a primary system 5. Despite being the most frequently cited system (74 validation studies), it has poor clinical discrimination because 1, 5:

• It fails to individually assess area, neuropathy, infection, and peripheral artery disease 1, 5
• Grades 4-5 are dominated by gangrene, rendering the system blunt 1
• Grade 3 lumps together all deep infections without distinction 5
• Studies validating it show high risk of bias and inconsistent results 1

Morphological and Severity Classification

Depth Classification (Universal)

• Superficial ulcers: Limited to epithelium and superficial connective tissue 1
• Deep ulcers: Extending to muscle, tendon, bone, or joint 1, 6

In diabetic patients, deep ulcers comprise 61.3% of cases overall, but this increases to 80% when both ischemia and infection are present versus 39% without these complications 6.

Oral Ulcer Morphological Features

• Aphthous ulcers: Well-demarcated, oval/round with white or yellow pseudomembrane and erythematous halo 1, 2
• Traumatic ulcers: Shape and location correspond to stimulating factor 1
• Tuberculosis ulcers: Stellate with undermined edges and clear boundary 1

Diagnostic Algorithm for Persistent or Atypical Ulcers

When to Escalate Investigation

For ulcers persisting beyond 2 weeks or not responding to 1-2 weeks of treatment, proceed with systematic investigation 1, 2:

First-line blood tests (required before biopsy) 1, 2:

• Full blood count (to detect hematologic diseases) 1
• Coagulation studies (to exclude biopsy contraindications) 1
• Fasting blood glucose (hyperglycemia predisposes to fungal infection) 1, 2
• HIV antibody testing 1, 2
• Syphilis serology 1, 2

Second-line testing when indicated 2:

• Nutritional deficiency screening: iron, folate, vitamin B12 2
• Autoimmune markers if autoimmune conditions suspected 2

Biopsy indications 1, 2:

• Any ulcer persisting >2 weeks despite appropriate treatment 1
• Atypical clinical features 1
• Suspicion of malignancy 2

Common Pitfalls to Avoid

• Never rely solely on clinical appearance without appropriate testing for persistent ulcers 2
• Never use only the total score of classification systems without describing individual clinical descriptors—this provides insufficient information for proper care 1, 5
• Never overlook systemic causes of recurrent oral ulcers, including nutritional deficiencies, autoimmune disease, and immunodeficiency 2
• Never assume all diabetic foot ulcers are purely neuropathic—63% have limb ischemia and 61% are neuroischemic 6
• Never treat symptoms without establishing a definitive diagnosis for persistent ulcers 2
• Never use Wagner classification to predict individual patient outcomes, as the quality of evidence for prediction is weak 5

Special Considerations in Diabetes

In diabetic foot ulcers, classification must account for the frequent coexistence of multiple pathologies 4, 6:

• Neuropathic ulcers: 37% of cases 6
• Neuroischemic ulcers: 61% of cases 6
• Pure ischemic ulcers: 2% of cases 6
• Infection present in 58% of cases 6

Neuropathy is present in 98% of diabetic foot patients, making it nearly universal, while limb ischemia affects 63% 6. This high prevalence of mixed pathology explains why multifactorial classification systems like SINBAD outperform single-dimension systems 1, 5.