Pathology · Year 2 · from Pathology
Case 3: Wound Healing by Secondary Intention
Patient Demographics
- Age: 68 years old
- Sex: Male
- Occupation: Retired, wheelchair-bound
Chief Complaint
"I have a sore on my buttock that won't heal"
History of Present Illness
A 68-year-old male with a history of spinal cord injury (T10 level) from a motor vehicle accident 5 years ago presents with a non-healing wound over his sacrum. He lives in a nursing home and is wheelchair-bound. Staff noticed the wound 6 weeks ago starting as a small red area that progressively worsened despite basic wound care. The wound has not improved and now has visible tissue at the base. He has type 2 diabetes (HbA1c 8.9%) and chronic kidney disease stage 3. He is incontinent of bladder and bowel. He reports no fever or chills.
Physical Examination
- Vital Signs: BP 128/78 mmHg, HR 72 bpm, Temp 36.8°C (98.2°F)
- General: Thin elderly male in wheelchair, appears comfortable
- Sacral region:
- 4 cm x 5 cm full-thickness wound over sacrum
- Wound extends through dermis into subcutaneous tissue
- Base shows mixture of red granulation tissue (60%) and yellow slough (40%)
- Wound edges show epithelial migration (pink rim)
- Moderate serosanguineous drainage
- Surrounding skin with mild erythema, no cellulitis or fluctuance
- Wound depth: 1.5 cm
- Neurologic: Absent sensation below T10
Diagnostic Workup
Laboratory Studies:
| Test | Result | Reference Range |
|---|---|---|
| WBC | 8,200/μL | 4,500-11,000/μL |
| Hemoglobin | 10.4 g/dL | 13.5-17.5 g/dL |
| Albumin | 2.8 g/dL | 3.5-5.5 g/dL |
| Pre-albumin | 12 mg/dL | 18-45 mg/dL |
| HbA1c | 8.9% | <7% |
| Creatinine | 1.9 mg/dL | 0.7-1.3 mg/dL |
| Zinc | 55 μg/dL | 60-120 μg/dL |
Wound Culture: Mixed flora including Staphylococcus aureus (MSSA), Proteus mirabilis
Wound Biopsy Histopathology:
- Granulation tissue with abundant new capillary formation (angiogenesis)
- Proliferating fibroblasts
- Mixed inflammatory infiltrate
- Collagen deposition (early scar formation)
- Myofibroblasts at wound edges (alpha-smooth muscle actin positive)
- Re-epithelialization from wound margins
Pathology Correlation
This case demonstrates wound healing by secondary intention:
- Phases of Wound Healing:
- Inflammatory phase (days 1-3): Platelet plug, neutrophil infiltration
- Proliferative phase (days 3-21): Granulation tissue, angiogenesis, epithelialization
- Remodeling phase (weeks to months): Collagen cross-linking, scar maturation
- Granulation Tissue Characteristics:
- New capillary loops (provide red, granular appearance)
- Proliferating fibroblasts synthesizing collagen
- Macrophages coordinating repair
- Loose extracellular matrix
- Key Growth Factors:
- PDGF (platelet-derived growth factor): Fibroblast chemotaxis
- VEGF (vascular endothelial growth factor): Angiogenesis
- TGF-beta: Collagen synthesis, fibrosis
- EGF/KGF: Epithelial cell migration
- Secondary Intention Characteristics:
- Large tissue defect requiring fill by granulation tissue
- Wound contraction by myofibroblasts
- Epithelialization from wound margins
- Results in larger scar than primary intention
- Factors Impairing Healing (present in this patient):
- Diabetes: Impaired neutrophil function, microangiopathy
- Malnutrition: Low albumin, low zinc
- Pressure: Continued ischemia to affected area
- Anemia: Reduced oxygen delivery
- Infection: Prolonged inflammatory phase
- Denervation: Lack of protective sensation
Clinical Image
Clinical photograph of a sacral pressure ulcer showing healing by secondary intention. The wound base contains beefy red granulation tissue with its characteristic granular appearance from new capillary loops. The wound edges show a thin pink rim of migrating epithelium. Yellow slough represents fibrinous debris that must be debrided to allow healing.
Image Source: Wikimedia Commons - "Decubitus ulcer" License: CC BY-SA 3.0 URL: https://commons.wikimedia.org/wiki/File:Stage_IV_sacral_decubitus_ulcer.jpg
Diagnosis
Stage 3 Pressure Ulcer (Sacral) with delayed healing due to multiple comorbidities
Treatment
- Pressure offloading:
- Specialty pressure-redistributing mattress
- Turning schedule every 2 hours
- Wheelchair pressure cushion
- Wound care:
- Sharp debridement of necrotic tissue
- Moist wound healing environment (foam dressing)
- Negative pressure wound therapy (VAC) to promote granulation
- Address modifiable factors:
- Optimize glycemic control (target HbA1c <7.5%)
- Nutritional supplementation (high protein, zinc, vitamin C)
- Correct anemia
- Infection management:
- Topical antimicrobial dressing
- Systemic antibiotics only if signs of cellulitis or sepsis
- Consider surgical closure:
- Flap coverage if wound fails to heal with conservative management
Teaching Points
- Healing by secondary intention occurs when wound edges cannot be approximated
- Granulation tissue is the specialized tissue that fills open wounds, rich in new capillaries and fibroblasts
- Myofibroblasts contract wounds to reduce surface area requiring epithelialization
- Growth factors (PDGF, VEGF, TGF-beta) orchestrate the phases of wound healing
- Diabetes impairs healing through multiple mechanisms: neutrophil dysfunction, microangiopathy, neuropathy
- Protein-energy malnutrition impairs collagen synthesis and immune function
- Pressure ulcer staging is based on depth: Stage 3 extends into subcutaneous tissue