July 01, 1997
Groups of small, membrane-bound vacuoles were noted in the cytoplasm, and after careful examination some of these were noted to contain striated structures (Figs. 2 and 3). Further searching of the cytoplasm revealed occasional elliptical shaped structures again with an internal lamellar or striated structure (Figs. 4 and 5). The latter were particularly typical of melanosomes prior to the accumulation of melanin pigment and, therefore, diagnostic for malignant melanoma. The diagnosis was later confirmed by immunocytochemistry positive for S-100 protein and HMB-45.
|
 Figure 2. Oval stage II melanosome with readily defined striated material internally. x105,000 |
 Figure 3. Narrow band of striations (arrow) at edge of melanosome with granular matrix. x73,000 |
|
 Figure 4. Vesicular structures some of which appear empty, have minimal granulofibrillar material or striations (arrow). x73,000 |
 Figure 5. Vesicular structures with concentric membranes, fine granules or striated material. x105,000 |
|
1996 | 1997 |
Society for
Ultrastructural Pathology© 1997 Society for Ultrastructural Pathology
All Rights Reserved