Recurrent conjunctival melanoma with neuroidal spindle cell features

Area of Science:

• Ophthalmology
• Dermatopathology
• Oncology

Background:

• Primary acquired melanosis (PAM) is a premalignant condition of the conjunctiva.
• Malignant transformation of PAM into conjunctival melanoma is rare.
• Spindle cell morphology in melanoma can present diagnostic challenges.

Observation:

• A 66-year-old woman with a 20-year history of conjunctival PAM developed multiple recurrences of invasive malignant melanoma.
• Two recurrences exhibited a nonpigmented spindle cell morphology.
• The most significant lesion was a 7.5 mm thick nodule of spindle cells with fascicular and neuroidal features.

Findings:

• The spindle cell melanoma mimicked neural tumors due to its fascicular arrangement and neuroidal appearance.
• Key diagnostic features included intraepithelial atypical melanocytes, absence of stromal mucopolysaccharides, mitotic activity, and lack of intercellular reticulin fibers.
• These findings confirmed the diagnosis of spindle cell invasive malignant melanoma.

Implications:

• This case highlights a rare morphologic variant of conjunctival melanoma.
• Accurate differentiation from neural tumors is crucial for appropriate patient management.
• Understanding this variant aids in the diagnosis and treatment of conjunctival neoplasms.