Perivascular spaces in eccrine spiradenoma. A clue to its histological diagnosis.

Perivascular spaces were found to represent a useful histological clue to the diagnosis of eccrine spiradenoma. They were observed in eight of nine eccrine spiradenomas but not in syringomas, nodular basal cell carcinomas, or glomangiomas. Perivascular spaces in spiradenomas consisted of variably sized spaces around one or more central blood vessels, bordered at the periphery by a palisade of tumor cells and lined at both sides by basement membrane collagen type IV. Perivascular spaces contained variable numbers of T lymphocytes in all cases and could undergo fibrosis, cystic dilatation, or hyalinization. In analogy to similar structures in thymomas, we suggest that perivascular spaces in spiradenomas are involved in the traffic of lymphocytes toward the tumor.