syringoma with dense stroma

SYRINGOMA WITH DENSE STROMA

It is mentioned but not emphasized in some texts that syringomas may have dense or desmoplastic stroma. Since syringomas have microcysts, small tumor strands, and fibrosis, it is useful to compare such a case with a desmoplastic trichoepithelioma, which also has microcysts, small tumor strands, and desmoplastic stroma. These features are also found in some cases of microcystic adnexal carcinoma and papillary eccrine adenoma.

Keratin is found more frequently in the microcysts of desmoplastic trichoepitheliomas, but some of the microcysts may appear to be empty as is true in syringomas. Microcysts in syringomas may, uncommonly, contain keratin. Tadpole or comma figures may be found in either tumor. The collagen bundles in fibrotic syringomas are larger than those that are wrapped around the tumor nests in desmoplastic trichoepitheliomas. Intracytoplasmic lumen formation is a feature of syringomas that is not characteristic of desmoplastic trichoepitheliomas.

Scan power view. The lesion is to the left of the arrow (JCT).

Low power view of above. Note the contrast in the character of the sun damaged dermis to the right of the arrow compared to the stroma of the tumor. Since the tumor stroma is eosinophilic, it is either refractory to sun damage or, more likely, this represents new collagen.

High power view of the tumor. The collagen bundles are much larger than those that surround the tumor nests in desmoplastic trichoepitheliomas.

Very high power view of above. Intracytoplasmic lumen formation is present, and this is a relatively reliable marker for an eccrine lesion rather than a follicular lesion.

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	Scan power view. The lesion is to the left of the arrow (JCT).
	Low power view of above. Note the contrast in the character of the sun damaged dermis to the right of the arrow compared to the stroma of the tumor. Since the tumor stroma is eosinophilic, it is either refractory to sun damage or, more likely, this represents new collagen.
	High power view of the tumor. The collagen bundles are much larger than those that surround the tumor nests in desmoplastic trichoepitheliomas.
	Very high power view of above. Intracytoplasmic lumen formation is present, and this is a relatively reliable marker for an eccrine lesion rather than a follicular lesion.