## 1 Introduction and General Overview  
Conjunctival melanoma (CM) is a rare ocular disease, accounting for about 2% of all ocular malignancies. Its incidence has been increasing in recent years, with 0.3-0.8 cases per million people in Western countries, mainly in Caucasian ethnicity, but can occur in African or in Afro-Americans as well. It most commonly appears in middle-aged or elderly white individuals. In the US, the incidence increased by 295% from 1973 to 1999 [1; 2; 3]. Usually, it arises from primary acquired melanosis (PAM), in about 75% of cases, less frequently from a pre-existing conjunctival nevus or de novo. CM arising from PAM appears as a thickening lesion. Histopathologicaly, PAM with mild atypia has less likelihood of transformation to melanoma than PAM with severe atypia [4]. De novo melanomas carry a higher risk of metastasis and death. As in cutaneous melanoma, sun exposure is a high risk factor and plays an important role in the pathogenesis of CM. Clinically, CM appears as a nodular or flat pigmented lesion, commonly located on the nasal or temporal bulbar conjunctiva (Figure 1), and, less frequently, as amelonic tumors. It has a tendency to spread directly to any part of conjunctiva, to the cornea, globe, eyelid, orbit, sinus or central nervous system, and through lympho-vascular drainage to the lierocervical lymph nodes or distant organs, as reported in the AJCC eighth edition staging system [5; 6]. Pathologic staging is based on vertical thickness and depth of invasion, and, consequently, it is classified as follows: \(\leq\)0.5, 0.5-1.5, and \(>\)1.5 mm. Breslow stages are not routinely used to classify CM. Biologically, CM shows different behavior than uveal melanoma, while it is quite similar to that of its cutaneous counterpart. Molecular characterization studies, developed to understand the tumor biology and possibly to implement any new therapeutic approaches, have confirmed this similitude with cutaneous melanoma. In particular, [PERSON] et al. found BRAF (of which, 91% were V600E) mutations in 29% and NRAS in 18% of conjunctival melanoma analyzed, similar to cutaneous melanomas [7]. Diagnosis requires a complete examination of bulbar and tarsal conjunctiva, as well as orbital rim, due to the high rate of recurrence in that region. Opthalmic examination, slit-lamp photography with clinical drawing, in vivo confocal microscopy (IVCM), optical coherence tomography (OCT), and ultrasound biomicroscopy (UBM) are variably used for documenting the localization and size of the lesion and to study its local extension. These non-invasive imaging techniques could support the diagnosis, but the excisional biopsy of a clinically suspicious lesion is undoubtedly the standard of care. CT and MRI of the orbit, maxillofacial region and brain are useful when an orbital, nasal and paranasal sinus or central nervous system involvement is suspected. Whole body PET/CT scan or MRI of the neck can reveal lymphatic spread to proximal nodes, and metastatic disease to regional lymph nodes is accessed using sentinel lymph node biopsy (SLNB) [8]. Surgery is the mainstay of treatment. [PERSON] introduced in 1997 the \"no touch\" technique, describing surgical guidelines to allow a complete en-bloc tumor removal with wide margins, avoiding direct tumor manipulation [9]. This technique is widely accepted and applied, in order to minimise cell seeding and reduce the likelihood of recurrence. Incisional biopsy is discouraged, as well as narrow-margin resection; a margin of at least 2 mm is generally advised, though some surgeons  
Figure 1: Slitlamp photograph of a conjunctival melanoma, histologically confirmed, with a tendency to invade the limbus and cornea. suggest 5 mm when possible. In case of suspect involvement of the Tenon capsule, or when there is any evidence of scleral adhesion or pigment, a local dissection to these structures should also be performed. Less frequently, CM presents as extensive infiltrating tumor, requiring enucleation or orbital exeneration.