Images (2)
Reflected light microscopy, saccular pattern
Synonym(s)
Saccular pattern
DefinitionThis section has been translated automatically.
Oval or polygonal, spherical or disk-shaped structures up to 0.45 mm in size, visible in the incident light plane, with different colour shades, e.g. yellowish-brownish, reddish-brownish grey, red-light brown, red-blue, slate grey. In American literature, the term predominantly stands for fluid-filled cavities, for example in the form of endothelium-lined cavities of the papillary stratum enriched with blood and/or lymph in hemangiomas.
General informationThis section has been translated automatically.
- Reflected light microscopy: Proliferating junctional cell nests project in the reflected light plane as sack-like structures histologically composed of atypical melanocytes. These melanoma cell agglomerates develop an uneven centrifugal growth in epidermis, junctional zone, papillary body or even within preformed hypertrophic dermal papillae. Depending on the pigment content or the degree of neovascularisation, saccules appear in different, mostly inhomogeneous colour shades. Rapidly growing, space-occupying melanoma cell nests of the stratum papillare dilate the dermal papillae and press the connective tissue contained therein against the reteleases or towards a neighbouring focus. This is accompanied by an inflammation-reactive fibrosis. In this way, whitish septations and negative reticular patterns are formed. Melanoma cells successively infiltrate and destroy the anatomically predetermined architecture of the papillary bodies, reteleases and appendages. The cell neoplasias grow at different rates. This results in an overall inhomogeneous reflected light microscopic image of small and large sacculi, which produce more or less large amounts of melanin, but can also be amelanotic. Transepidermally secreted pigment can overlay the original focus and simulate a localization of the saccules in the upper epidermal layers.
OccurrenceThis section has been translated automatically.
Individually or grouped in malignant melanomas of higher invasion levels (Clark level III-IV), with a specificity of well over 90% in relation to melanocytic lesions. The sensitivity is about 22%.
Differential diagnosisThis section has been translated automatically.
Cobble stone patterns in benign nevi are limited by keratin stripes. They show uniform and symmetrically distributed brown pigmentation. In lacunar patterns of hemangiomas neither the transepidermal pigment exudations typical for sacculi nor traces of a pigment network exist. The lacunae are symmetrically arranged, uniformly round or oval, compact and uniformly tinged by haemoglobin or its degradation products.
LiteratureThis section has been translated automatically.
- Kenet RO et al (1993) Clinical diagnosis of pigmented lesions using digital epiluminescence microscopy. Arch Dermatol 129: 157-174
- Menzies SW, Ingvar C, McCarthy WH (1996) A sensitivity and specificity analysis of the surface microscopy features of invasive melanoma. Melanoma Res 6: 55-62
- Schulz C, Stücker M, Schulz H, Altmeyer P, Hoffmann K (1999) Correlation of incident light microscopic characteristics of malignant melanomas with the tumor invasion levels according to Clark. dermatologist 50: 785-790
- Schulz H (2001) Reflected light microscopic vital histology. Dermatological guide. Springer, Berlin Heidelberg New York