A rare case of acantholytic squamous cell carcinoma presenting on non-sun exposed palpebral conjunctiva.

Purpose: This report describes the clinical and histological characteristics and management of a keratinized lesion of the palpebral conjunctiva in a 59-year-old male. The lesion was identified as a rare acantholytic variant of squamous cell carcinoma that atypically arose from a non-sun exposed region of palpebral conjunctiva. Management was complete excision via Mohs surgery. Observations: A 59-year-old male presented with ocular irritation and chronic foreign body sensation in the right eye. Exam revealed a keratinized lesion in the right lower tarsal conjunctiva, and an initial shave biopsy was non-diagnostic. 12 months later, the patient presented with similar symptoms and a larger, more irregular lesion for which histopathology of a tarsal-involving excisional biopsy was consistent with acantholytic squamous cell carcinoma with involved margins. The patient subsequently underwent complete excision via Mohs surgery and a secondary reconstruction. Conclusions and importance: Acantholytic variants of squamous cell carcinoma are rare and are described as arising from areas with routine sun exposure. This case reports such a lesion arising from non-sun exposed tarsal conjunctiva, as identified by histopathology of a full-thickness excisional biopsy. The lesion was successfully managed with complete excision via Mohs surgery and secondary reconstruction. Given that this histologic variant may be more aggressive and have higher rates of recurrence than other forms of squamous cell carcinoma, this case highlights the importance of complete excisional biopsy and accurate histopathology of concerning periocular lesions and offers a template for management of similar lesions. The unique presenting location should bring awareness to consideration of this type of malignancy developing on palpebral conjunctiva.