Squamous cell carcinoma arising from giant porokeratosis and rare postoperative recurrence and metastasis: A case report

RATIONALE: Giant porokeratosis is considered to be a variant of porokeratosis of Mibelli (PM) by some medical scholars. Porokeratosis can develop into several epidermal malignant tumors, such as Bowen disease and basal cell carcinoma, among which squamous cell carcinoma (SCC) is the most common. PATIENT CONCERNS: The patient was a 53-year-old man who was admitted to our hospital due to postoperative recurrence and metastasis as SCC arising from giant PM in his left leg and foot. DIAGNOSES: The pathological results are porokeratosis and well-differentiated squamous cell carcinoma. Positron emission tomography and computed tomography results show the local recurrence of the tumor with multiple lymph node metastasis. INTERVENTIONS: This patient was transferred to orthopedic surgery for amputation of the middle and lower left thigh. OUTCOMES: Follow-up for 3 months has shown no recurrence after the surgery. LESSONS: This report reminds us to pay close attention to the likelihood of giant porokeratosis. The physicians should explore all clinical possibilities to avoid misdiagnosis of this rare disease. Although the recurrence rate of SCC arising from giant PM is very low, the surgical resection region should be expanded appropriately such as the en-block resection.