How do you differentiate between an epidermal inclusion cyst and a dilated pore of Winer in adults?

Differentiating Epidermal Inclusion Cyst from Dilated Pore of Winer

The key distinguishing feature is the presence of a visible central pore: a dilated pore of Winer presents as a giant comedo with a prominent keratin-filled opening on the skin surface, while an epidermal inclusion cyst appears as a subcutaneous nodule without a visible surface opening. 1

Clinical Presentation

Dilated Pore of Winer

• Appears as a giant comedo with a visible central pore plugged with keratin material 1, 2
• Characterized by annular elevation of the borders surrounding the central opening 1
• Typically located on the facial area of elderly patients 1
• The eccentric pore is the hallmark feature that distinguishes it from other lesions 2
• May be mistaken for basal cell carcinoma or senile sebaceous adenoma due to the raised borders 1

Epidermal Inclusion Cyst

• Presents as a subcutaneous, well-circumscribed, mobile nodule without a visible surface opening 3, 4
• Usually asymptomatic unless complicated by rupture or infection 3
• When inflamed, becomes painful and tender, potentially mimicking an abscess 3
• Contains cheesy keratinous material and normal skin flora even when uninflamed 3, 5

Imaging Characteristics

Ultrasound Findings for Epidermal Inclusion Cyst

• Well-circumscribed (96%), ovoid-shaped (78%) mass 4
• Heterogeneously and mildly echogenic (92%) with increased through-transmission (92%) 4
• Low echoic rim (67%) surrounding the lesion 4
• Internal debris may show linear echogenic reflections (17%) or dark clefts (18%) 4
• No Doppler flow in 97% of cases 4

Ultrasound Findings for Dilated Pore of Winer

• Shows hyperechoic components with acoustic shadowing 3
• May demonstrate hyperechoic lines and dots 3
• Sometimes exhibits fluid-fluid levels 3

Histopathologic Differentiation

Dilated Pore of Winer

• Shows typical infundibular dilatation that opens widely to the skin surface 1, 2
• Subinfundibular atrophy of hair structures is characteristic 1
• Wall displays proliferation of rete ridge-type structures projecting into surrounding dermis 2
• Filled with flaky keratin material 2

Epidermal Inclusion Cyst

• Completely enclosed cyst without surface communication 3
• Contains keratinous material within a closed cavity 3, 5
• Inflammation results from cyst wall rupture and extrusion of contents into dermis, not primary infection 3, 5

Management Approach

For Dilated Pore of Winer

• Simple excision is curative with no reported recurrence 2

For Epidermal Inclusion Cyst

• Incision with thorough evacuation of contents, probing the cavity to break up loculations, and dry dressing application 3, 5
• Systemic antibiotics rarely necessary unless complications exist (multiple lesions, extensive cellulitis, severe systemic manifestations, or immunocompromise) 3, 5
• Gram stain and culture typically unnecessary 5

Clinical Pitfalls

• The raised borders of dilated pore of Winer can mimic basal cell carcinoma—the visible central pore is the distinguishing feature 1
• Inflamed epidermal inclusion cysts may be mistaken for abscesses, but the inflammation is a sterile foreign body reaction to cyst contents, not infection 3, 5
• Do not confuse epidermal inclusion cysts with dermoid cysts, which contain more complex structures like hair, teeth, and cartilage due to their congenital developmental origin 3