Clinical Cytology in the Diagnosis and Management of Melanoma

Melanoma, an aggressive tumor of the melanocytes is more prevalent among the white-skinned individuals with the highest incidence reported from Australia and New Zealand (Elwood M,2002). Primary melanomas usually involve the skin, mucosa, retina and leptomeninges. They are known to metastasize to lymph nodes, lung, liver and virtually any part of the body (Basler et al., 1997; Saqi et al., 2002; Ustün et al., 2002; De Las Casas et al., 2004; Parwani et al., 2004; Mohr et al., 2009). Surgical excision with adequate margins is the treatment of choice for cutaneous melanoma. The prognosis of melanoma varies with the site and stage of the disease (Damala et al., 2004; Mohr et al., 2009). Advanced disease with local recurrence, or distant metastasis carries a grave prognosis (Saqi et al., 2004). A variety of imaging techniques such as the chest and abdominal computed tomography (CT) scan, magnetic resonance imaging (MRI) of the brain and positron emission tomography (PET) are used in the staging work-up of patients with cutaneous melanoma, chiefly, for evaluating the potential metastatic sites such as the lungs, lymph nodes, liver and brain. An imaging work-up is generally not recommended in patients with a <1.0 mm thick lesion, as the cure rate in such cases is >90%. It is also not essential in patients with primary melanoma thicker than 1.0 mm, wherein a sentinel lymph node biopsy (SLNB) serves as a better staging tool (Mohr et al., 2009). Justifiably, histologic examination of the surgical biopsies plays a major role in the diagnosis of primary and metastatic melanomas. Nonetheless, role of non-invasive/ minimally invasive cytologic techniques has also been adequately addressed (Rai, 2007). The cytologic techniques vary with the nature and location of the lesion and these include fine needle aspiration cytology (FNAC), imprint cytology (IC), scrape cytology, as well as, the examination of exfoliative samples such as the serous body fluids, sputum, cerebrospinal fluid (CSF) and synovial fluid (Paridaens et al., 1992; Deshpande et al., 2001; Saqi et al., 2002; Ali et al., 2005). Of these, FNAC is widely employed and its primary role is to confirm the metastatic or recurrent melanoma lesions (Saqi et al., 2002; Mágori, 2003; Siddaraju et al., 2007). By cytologic means, various authors have been able to detect metastatic melanoma deposits in a wide variety of sites inclusive of adrenal, kidney, omentum, pancreas, parotid, soft tissue, spine, breast, thyroid and brain (Saqi et al., 2002; Artal et al., 2004; Hernandez et al., 2004; Gombos et al., 2004; Bozbora et al., 2005; Kung et al., 2009; Kaneko et al., 2009). Not infrequently, cytology is used for diagnosing primary melanoma as well (Layfield et al., 1993; Dey et al., 1996; Gupta et al., 2003; Mágori, 2003; Kotoulas et al., 2007). A significant