Keratoacanthoma with perineural invasion: an indicator for aggressive behavior?

Area of Science:

• Dermatology
• Oncology
• Surgical Pathology

Background:

• Keratoacanthoma (KA) is a common skin tumor, typically benign with a high rate of spontaneous regression.
• Neurotropic invasion, the spread of tumor cells along nerves, is an uncommon finding in KA.
• Perineural invasion in KA is often overlooked due to the tumor's usual self-limiting nature.

Observation:

• A 36-year-old woman presented with a rapidly growing keratoacanthoma on her upper lip following CO(2) laser resurfacing.
• Histopathological examination revealed perineural invasion within the KA.
• The lesion recurred despite multiple intralesional methotrexate treatments.

Findings:

• Immunohistochemistry demonstrated reduced desmoglein 1 expression, a feature typically associated with squamous cell carcinomas.
• The patient achieved a sustained tumor-free status for over three years after receiving 56 Gy of ionizing radiation.
• This case suggests that perineural invasion in head and neck KAs may signify a more aggressive clinical behavior.

Implications:

• Perineural invasion in keratoacanthoma warrants careful consideration and may indicate a need for more aggressive management.
• Histologically-controlled excision should be recommended for head and neck KAs exhibiting perineural invasion.
• Further research is needed to understand the prognostic significance of neurotropic invasion in KA.