Inverted Follicular Keratosis of the Lower Eyelid-A Diagnostic Conundrum.

Background: Ulceroproliferative lesions involving the eyelids can be due to several causes, chief among them being squamous cell carcinoma (SCC). It is imperative to distinguish it from various mimics owing to the limited surgical therapy that can be offered at the site. Inverted follicular keratosis (IFK) is a rare benign epidermal tumor that arises from the infundibular portion of the hair follicle. The endophytic growth pattern and histological features closely mimic SCC especially in small or superficial biopsies, making accurate diagnosis challenging.

Case presentation: A 76-year-old male patient who presented with a nodular ulcerative lesion on the right lower eyelid that gradually increased in size over a span of 20 years. The lesion was excised through pentagonal full-thickness resection with 2-mm margins. Primary closure was achieved with the aid of lateral canthotomy to reduce tension. The postoperative course was uneventful. Wound healing was complete with normal eyelid closure and no ectropion. Histopathological examination revealed features characteristic of IFK, including an endophytic proliferation of basaloid and squamous cells, numerous squamous eddies, keratin-filled cysts, and absence of cellular atypia or mitotic activity. p53 immunohistochemistry showed wild-type expression, supporting the benign nature of the lesion.

Conclusions: IFK can clinically and histologically resemble SCC, particularly in limited biopsy samples. Surgical excision with appropriate margin clearance and functional eyelid reconstruction ensures both curative and functional outcomes. Awareness of this benign entity and recognition of its distinguishing histopathological features are crucial to avoid overtreatment and to ensure appropriate patient management. Complete excision remains the treatment of choice and has excellent prognosis.