unusual neoplastic recurrence in the corneo-scleral limbus: recurrent atypical fibrous histiocytoma followed by intra-epithelial squamous neoplasia

purpose: to report the clinical and histopathological features of recurrent atypical fibrous histiocytoma of the corneo-scleral limbus followed by intra-epithelial squamous neoplasia. case report: a 25-year-old female patient presented with a recurrent vascularized gelatinous mass in the left nasal limbus. the preliminary histopathological diagnosis of the previously excised lesion was an amelanotic malignant melanoma at a private general pathology center. the lesion had recurred after one year and the histopathologic diagnosis was a poorly differentiated malignant melanoma at another pathology center. the lesion recurred again and the specimen was sent to a third histopathologic center where the histopathologic diagnosis revealed spindle cell growth with moderate atypia. a pannus-like lesion occurred in the nasal limbus 3 years later which was excised and sent to the eye bank pathology laboratory. reviewing the slides related to the first recurrent lesion and the histopathologic examination of the recently excised specimen disclosed a final diagnosis of atypical fibrous histiocytoma and intra-epithelial squamous neoplasia, respectively. conclusion: fibrous histiocytoma is a rare limbal tumor that may have atypical features and can be misdiagnosed as an amelanotic melanoma. this is also a rare report on the occurrence of intraepithelial squamous neoplasia following excision of recurrent fibrous histiocytoma.