Glypican-3 protein expression in melanoma: A immunocytochemistry study N. Gursan * , H. Balta, B. Gundogdu * Ataturk University, Medical Faculty, Erzurum, Turkey Objective: Glypican-3 (GPC3) is a cell surface heparan sulfate proteoglycan. Serum GPC3 was shown to be expressed in 40 % of melanomas (Ms) but GPC3 expression in Melanoma tissues had not been investigated.In this study, immunohistochemical analysis of GPC3 protein expression was investigated in histologic sections from Melanoma tissues. Method: 60 melanoma patients, twenty patients with insitu melanoma, twenty patients stage 0 and stage I melanoma, twenty patients stage II and stage III melanoma. All cases were stained with anti-GPC3 antibody. GPC3 expression was divided into 2 categories: negative (negative or weak cytoplasmic staining) and positive (moderate or strong cytoplasmic with membranous accentuation). Results: GPC3 immunopositivity. showed in 40,3 % of melanomas. GPC3 expression at stage 0, I, II, III were 44.4 %, 40.0 %, 41.6 %, 35 % respectively. Method: We report the case of a 77 year old man presenting with an erythematous plaque of the right hemithorax. Results: Macroscopically the lesion had irregular borders and was mildly infiltrative with a violet hue. Microscopic examination revealed tumor cells within lymphatic spaces, without infiltration of the adjacent stroma. The histologic and immunophenotypic characteristics of these cells were compatible with a carcinoma of lung origin. CT scan revealed a lung mass as well as multiple liver and chest wall metastases. Conclusion: Malignancies originating from the breasts, lungs and large bowl are the most common to involve the lymphatic net of the skin. Melanoma on the other hand is more frequently presenting with lymphangitic invasion, whereas inflammatory carcinomas may also affect lymphatic vessels and may be confused with erysipelas. The revelation of the primary origin is not always easy and differential diagnosis should also include gynecological malignancies, kidney and urinary bladder carcinomas. In our patient the diagnosis was established on the grounds of histology and immunohistochemistry, and was supported by the clinical and radiological findings. Objective: Inverted follicular keratosis (IFK) is almost always a solitary lesion occuring mainly in adult life. Men are affected twice as often as women. Pathologically, They can be confused with a variety of lesions, both benign and malignant. Squamous carcinoma is the most serious differential diagnosis. Method: We decribe a retrospective study about 7 cases of IFK diagnosed over a 18-year-period (1994-2012) . Results: We collected 7 lesions, all treated by surgical excision. Haemalum eosin sections were studied in all cases. All lesions were single. Five, of them, were situated on the face and two on the scalp. All the patients were adults with a mean age of 34 years, average between 19 and 66 years. They presented mostly as asymptomatic papules and all were small lesions. The different sections of the lesion showed skin well delineated endophytic epithelial proliferations with inverted papillomatous and acanthotic components containing several circumscribed squamous eddies. They was no atypia, mitotic activity necrosis or stromal invasion. Conclusion: IFK pose very real diagnostic problems unless one is aware of this entity. In fact, they may mimic malignant lesions especially squamous cell carcinoma, both clinically and pathologically.