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Primary macular amyloidosis: an ultrastructural approach to diagnosis
C Schepis1, M Siragusa, M E Gagliardi
1Unit of Dermatology, Oasi Institute (IRCCS), Troina, Italy.
Abstract:
Seven cases of primary macular amyloidosis were studied on skin biopsies. The Congo red stain was positive only in three cases, whereas the ultrastructural observation allowed for the detection of amyloid deposits in all biopsies. Fibrillary degeneration of basal keratynocytes was occasionally observed, and regressive changes of keratynocytes and dermal nerve bundles presumably related to the intensity of the scratch trauma were detected in one case. In six biopsies mast cell profiles exhibiting various degrees of degranulation were detected in the dermis. Melanosome aggregates were also observed consistently in dermal macrophages and occasionally in Schwann cells. A variable degree of structural alteration was observed in dermal unmyelinated nerve fibers. Even if the intimate mechanism of amyloid deposition was not explained by the ultrastructural study, this approach is a useful instrument in the differential diagnosis of cutaneous macular hyperpigmented lesions.
Insights
Ultrastructural examination of skin biopsies is crucial for diagnosing primary macular amyloidosis, detecting amyloid deposits missed by Congo red staining in some cases. This method aids in differentiating hyperpigmented skin lesions.
Area of Science:
- Dermatology
- Pathology
- Electron Microscopy
Background:
- Primary macular amyloidosis presents as a cutaneous condition causing hyperpigmented macules.
- Traditional diagnostic methods like Congo red staining have limitations in detecting amyloid deposits.
Purpose of the Study:
- To evaluate the utility of ultrastructural analysis in diagnosing primary macular amyloidosis.
- To compare ultrastructural findings with Congo red staining results.
Main Methods:
- Skin biopsies from seven patients with primary macular amyloidosis were examined.
- Conventional light microscopy with Congo red staining was performed.
- Transmission electron microscopy was utilized to analyze ultrastructural features.
Main Results:
- Amyloid deposits were detected in all seven biopsies via ultrastructural observation.
- Congo red staining was positive in only three of the seven cases.
- Associated findings included mast cell degranulation, melanosome aggregates in macrophages and Schwann cells, and alterations in dermal nerve fibers.
Conclusions:
- Ultrastructural examination is a highly sensitive method for detecting amyloid deposits in primary macular amyloidosis.
- Electron microscopy is a valuable tool for the differential diagnosis of cutaneous macular hyperpigmented lesions, especially when Congo red staining is inconclusive.