1. Differential Diagnosis

• Lichen Planus: Characterized by pruritic, polygonal, flat-topped papules with Wickham striae.
• Psoriasis: Can present with shiny papules but typically has a silvery scale.
• Eczema: May have similar pruritic lesions, but typically with more inflammation and scaling.
• Drug Eruptions: Consider medications or substances, but the absence of a new medication history may reduce this likelihood.
• Viral Exanthems: Certain viral infections can present with papular lesions.
• Other Dermatoses: Consider conditions like fixed drug eruptions or contact dermatitis.

2. Clinical Assessment

The description of "shiny, flat-topped, violaceous papules" along with the presence of Wickham striae is highly suggestive of Lichen Planus. Additionally, the pruritus and location of lesions (flexor surfaces) further support this diagnosis. While the patient’s pending Hepatitis C serology is essential, it does not necessarily change the initial approach to treatment given the clinical picture.

3. Recommended Next Steps (Labs/Imaging)

• Punch Biopsy: While clinical diagnosis of Lichen Planus is often sufficient, a punch biopsy can confirm the diagnosis, particularly in atypical cases or if there is a need to rule out other conditions.
• Hepatitis C Serology: Continue to monitor results of pending lab tests, as Hepatitis C can be associated with Lichen Planus.
• Consider additional labs: If systemic involvement is suspected, check for liver function tests.

4. Treatment Recommendations

• High-Potency Topical Steroids: Initiate treatment with high-potency topical steroids (e.g., clobetasol propionate) to alleviate pruritus and inflammation.
• Considerations for Follow-up: Monitor the patient's response to treatment and reassess within 4-6 weeks. If no improvement occurs or if the diagnosis is uncertain, proceed with a punch biopsy.
• Patient Education: Inform the patient about the nature of Lichen Planus, potential triggers, and the importance of follow-up.

In summary, while a clinical diagnosis is feasible, a biopsy can provide additional confirmation, especially in atypical presentations. Immediate treatment can be initiated based on the clinical findings.