Musculoskeletal and Skin Pathology for Medical II Students

Lab 2d Nodular Melanoma, Clark's Level V (01000-87703)

Malignant melanoma can arise de novo or from a pre-existing melanocytic nevus. Its appearance can vary, ranging from an irregularly contoured, relatively flat lesion with variegated pigmentation, to a sharply demarcated blue-black nodule. There are currently four "types" of melanoma, categorized by both clinical and microscopic features: superficial spreading melanoma, showing "pagetoid" spread of atypical melanocytes in the epidermis as well as dermal invasion; lentigo maligna melanoma, with proliferation of atypical melanocytes singly along the junctional region of an atrophic epidermis; acral lentiginous melanoma, showing often large, dendritic melanocytes along the junctional zone, especially on the palms and soles; and nodular melanoma, in which there is minimal intraepidermal spread but extensive dermal/subcutaneous invasion. Prognosis is determined by Clark's level of invasion and by Breslow's thickness measurement, determined by measuring in millimeters the distance between the top of the epidermal granular cell layer and the deepest extent of the melanoma into the dermis or subcutis. The exhibited slide shows a nodular melanoma of Clark's level V, which indicates involvement of the subcutaneous fat. Among primary malignant melanomas, a tumor with these characteristics tends to have the poorest prognosis.

Slides D14 & D15a | Slides D15b & D16

Slide D15b Low power view showing the melanoma extending from the epidermis deep into the cutis and laterally under adjacent intact epithelium.

Slide D16 Mid-high power with pigmented tumor cells showing the irregular arrangement of the tumor, the invasion of the epidermis, the edge of an ulceration on the left and crust (scab) formation. Compare the junctional activity of these malignant cells (the cells appear to be present in both epidermis and dermis and appear to "drop off" the epidermis) with the intradermal location of neval cells of the intradermal nevus seen previously.

Digital Legends for Labs/Cases
Lab 1
1a | 1b | 1c | 1d | 1e | 1f | 1g
Gross & Radiographs
a | b | c | d | e | f | g | h 
Lab 2
2a | 2b | 2c | 2d | 2e | 2f

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Updated August 28, 2007