S90.423S Blister (nonthermal), unspecified great toe, sequela

Name of the Condition

• Blister (nonthermal), unspecified great toe, sequela (ICD-10 code: S90.423S)

Summary

A blister (nonthermal) of the unspecified great toe, sequela, refers to a residual or chronic condition resulting from a prior nonthermal blister injury to the great toe. This sequela involves persistent or recurrent fluid collection beneath the skin, often due to incomplete healing or tissue changes following the initial injury. The condition may cause ongoing discomfort, altered skin texture, or reduced function of the toe, depending on the extent of residual damage.

Causes

The sequela arises from a previous nonthermal blister injury to the great toe, typically caused by friction, minor trauma, or prolonged pressure. Incomplete healing, scarring, or tissue remodeling after the initial injury can lead to persistent blistering or related skin changes.

Risk Factors

• History of prior nonthermal blister injury to the great toe.
• Delayed or inadequate treatment of the initial blister.
• Underlying conditions affecting skin healing (e.g., diabetes, vascular disease).
• Recurrent friction or pressure on the affected toe.

Symptoms

• Persistent or recurrent fluid-filled sac on the great toe.
• Chronic pain, tenderness, or itching at the site.
• Altered skin texture, such as thickening or scarring.
• Reduced mobility or discomfort with footwear.

Diagnosis

Physical examination of the great toe to assess residual blistering, scarring, or tissue changes. Review of the patient’s medical history to confirm a prior nonthermal blister injury and evaluate the timeline of symptom onset. Imaging or additional tests may be used to rule out other conditions if needed.

Treatment Options

• Protective measures to reduce friction (e.g., padding, proper footwear).
• Topical treatments to manage pain or itching.
• Wound care for persistent blisters or open areas.
• Referral to a specialist for severe or nonhealing sequela.

Prognosis and Follow-Up

Prognosis depends on the extent of residual tissue damage and adherence to treatment. Most cases improve with proper care, but chronic symptoms may persist. Follow-up appointments monitor healing and adjust treatment as needed.

Complications

• Chronic pain or discomfort.
• Infection of residual blisters.
• Permanent skin changes or scarring.
• Reduced toe function or mobility.

Lifestyle & Prevention

• Wear well-fitting, supportive footwear to minimize friction.
• Use protective padding or moleskin for high-risk activities.
• Maintain good foot hygiene to support healing.
• Address underlying conditions that impair skin repair.

When to Seek Professional Help

Seek care if symptoms worsen, signs of infection develop (e.g., redness, pus), or the sequela interferes with daily activities. Prompt evaluation is important for persistent or severe cases.

Tips for Medical Coders

Document the sequela status and its relationship to the prior nonthermal blister injury. Ensure the code S90.423S is used only when the condition is a direct result of a previous injury and is reported as a sequela. Include details about the residual effects (e.g., scarring, chronic pain) to support coding accuracy.