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Occurrence of melanin in pheochromocytoma
S K Landas1, C Leigh, S M Bonsib
1Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City.
Abstract:
Melanin or a melanin-like pigment was observed in six of 19 pheochromocytomas. The intracellular pigment was Fontana-positive, bleach-labile dark brown to black material and distinct from coincidental hemosiderin and lipochrome. Ultrastructural components of the pigmented tumors include melanosomes and premelanosomes. Two patients with pigmented tumors had associated von Hippel-Lindau syndrome, and one had neurofibromatosis. The occurrence of melanin and melanosomes in pheochromocytoma has not been previously reported in the English literature. It is probably a reflection of the neural crest origin of this neoplasm.
Insights
Melanin pigment was found in six pheochromocytomas, a rare finding. This suggests a link between these neural crest-derived tumors and pigment-producing cells.
Area of Science:
- Oncology
- Pathology
- Genetics
Background:
- Pheochromocytomas are rare tumors arising from chromaffin cells in the adrenal medulla.
- The neural crest origin of pheochromocytoma suggests a potential for differentiation into various cell types.
Purpose of the Study:
- To investigate the presence and characteristics of melanin pigment in pheochromocytomas.
- To explore the potential implications of pigment presence for tumor origin and associated syndromes.
Main Methods:
- Histochemical analysis using Fontana staining to identify melanin.
- Microscopic examination to differentiate pigment from hemosiderin and lipochrome.
- Ultrastructural analysis to identify melanosomes and premelanosomes.
Main Results:
- Melanin pigment was observed in 6 out of 19 (31.6%) pheochromocytomas.
- The pigment was Fontana-positive, bleach-labile, and distinct from hemosiderin and lipochrome.
- Ultrastructural examination revealed melanosomes and premelanosomes in pigmented tumors.
- Two patients with pigmented pheochromocytomas had von Hippel-Lindau syndrome; one had neurofibromatosis.
Conclusions:
- The presence of melanin and melanosomes in pheochromocytoma is reported for the first time in the English literature.
- Pigmentation in pheochromocytoma likely reflects its neural crest origin.
- This finding may have implications for understanding tumor differentiation and potential associations with genetic syndromes.