Background: Although the presence of tumour infiltrating lymphocytes (TIL) is a constant feature in melanomas, their immunophenotypic characterisation is still incomplete. We hypothesise that the transition from normal skin to benign naevi (BN) to melanocytic dysplastic naevi (MDN) to radial growth phase cutaneous malignant melanoma (RGP-CMM) to vertical growth phase cutaneous malignant melanoma (VGP-CMM) is associated with alterations in TIL. This study attempted to test this hypothesis and to characterise TIL in the melanocytic skin lesions. Methods: In total, 74 lesions (12 BN, 12 MDN, 13 RGP-CMM, 26 VGP-CMM, and 11 metastatic melanomas) were examined using immunoperoxidase staining methods and antibodies targeting leukocyte common antigen (LCA+), T (CD3+) and B (CD20+) lymphocytes, and resting cytotoxic T cells (TIA-1+). Results: Histologically, the transitions from normal skin to BN to MDN to RGP-CMM to VGP-CMM was associated with a gradual increase in the numbers of TIL (total, parenchymal, stromal, perivascular, and epidermal TIL, as well as TIL at the base of the lesions). The numbers of TIL were higher at the stroma than at the parenchyma. Similarly, immunostaining revealed that these transitions were associated with a gradual increase in the staining values (staining intensity, percentage of positive cells, and immunoreactivity score) for LCA+, CD20+, CD3+, and TIA-1+cells. The number of CD3+ cells was higher than that of CD20+ cells. All these differences between the normal skin and the lesional ones reached statistical significance (p,0.01). The majority of CD3+ cells were TIA-1+ T cells with cytotoxic potential. Compared with primary melanomas, there was a decrease in TIL in metastatic melanomas. Conclusions: The gradual increase in TIL during melanoma tumorigenesis may reflect increased antigenicity of the tumour cells. Although both humoral and cell mediated immunity are involved in melanomagenesis, the latter seems to have the major role. The immune profile of MDN suggests their intermediacy between BN and CMM.

Although melanocytic skin lesions have been recognized since antiquity, their literature was limited to Caucasians. To date, the clinicopathologic features of these lesions in Egyptians are still unknown. To define these features, diagnostic records of the melanocytic skin lesions received at the Pathology Department, Assuit University Hospitals (1989-2004) were reviewed. The lesions examined included 12 benign naevi (BN), 10 dysplastic naevi (DN), and 21 cutaneous malignant melanomas (CMMs). The DN and CMMs were more common in men than in women (2 : 1 and 1.5 : 1, respectively) while BN were more common in women (2 : 1). The average age incidence was 33+/-5, 38+/-7 and 54+/-3 years, for BN, DN and CMM, respectively. The lower limb (13/21, 62%), head and neck (7/21, 33%) were the most common sites for CMMs. The average size (mm) was 2+/-0.3, 4+/-0.6 and 21+/-0.3 for BN, DN and CMMs, respectively. Recurrence occurred in 10% of CMMs. Histologically, CMMs were of nodular type and composed of epithelioid (7/21, 33%), spindle cells (1/21, 5%), or mixed cells (13/21, 62%). The mean tumour thickness (Breslow) was 6+/-0.5 mm. CMMs included two of 21(9%), three of 21(14%), six of 21(38%), and 10 of 21(38%) with Clark level II, III, IV and V. In Egypt, CMM is the third most common cutaneous neoplasm following squamous and basal cell carcinomas. Compared with Western societies, melanoma has a male sex predilection, similar histological features but different topographical distribution and rare incidence. The striking difference from Western series is the incidence of nodular melanoma - in the West this represents 15-30% of melanomas, with superficial spreading being the majority. Another key difference from the West is the 'sun-bed' culture of the West and the desire to have suntans. This is the first study that reports the clinicopathologic features of melanocytic skin lesions in Egypt.