BACKGROUNDPrimary pleuropulmonary synovial sarcoma (SS) is a rare neoplasm and a recently recognized anatomic subset. Its clinicopathologic attributes are not yet well defined.METHODSIn this study, the clinical and histopathologic features of 12 SS arising in the lung and/ or pleura were analyzed.RESULTSThe neoplasms occurred in 7 men and 5 women, 20–72 years old (median, 31 years), were well circumscribed with a mean size of 7.2 cm, and involved either lung (9 cases), pleura (2 cases), or both (1 case). All the tumors were of monophasic type. Nine showed a classic spindle cell pattern, and three showed predominantly poorly differentiated features. All but one case showed at least focal positivity for epithelial membrane antigen (EMA), a finding characteristic of this tumor. The lack of EMA staining in one case, proven by electron microscopy to be SS, was attributed to the scarcity of material available for immunohistochemical stains. The diagnosis was proven cytogenetically in three cases. Within 2 years, local recurrence developed in 8 patients (75%), 3 of whom developed metastasis (25%). Five patients died of their disease within 2.5 years, 4 of them from uncontrolled local disease.CONCLUSIONSThe authors conclude that pleuropulmonary SS, although rare, represents a distinct anatomic subset having pathologic features similar to those of its soft tissue counterpart. Its clinical behavior appears more aggressive, perhaps because of relatively later presentation combined with the difficulty in obtaining a wide surgical margin. Cancer 2002;94:459–69. © 2002 American Cancer Society.

Sclerotic fibroma was first described in association with Cowden's disease by Weary et al. in 1972. In 1989, Rapini and Golitz detailed 11 cases of solitary sclerotic fibroma (SFS) in the absence of Cowden's disease, suggesting the term SFS of the skin. Classic histological features include hypocellular, hyalinized bands of collagen sharply demarcated from the surrounding skin. Numerous authors have described sclerotic fibroma-like changes in other entities including melanocytic nevi, dermatofibromas, lipomas, tendon sheath fibromas, giant cell collagenomas, neurofibromas, angiofibromas, erythema elevatum diutinum, and folliculitis. Dissension has arisen, with some dermatopathologists asserting that sclerotic fibroma is just an evolutionary end-point of a previous lesion. Others contend that SFS is a distinct lesion and cite recurrent cases and/or proliferation marker studies to corroborate this view. We detail the histopathological findings of lesions consistent with the classic description of SFS and compare these to sclerotic changes observed in an intradermal nevus, blue nevus, erythema elevatum diutinum, neurofollicular hamartoma, angiofibroma, neurofibroma, accessory nipple, and dermatofibromas. Sclerotic fibroma-like change may be seen in a variety of lesions and may represent a common reaction pattern in the skin.

The non-Langerhans histiocytoses, a nosologic category to which juvenile xanthogranuoma (JXG) belongs, represent a heterogenous collection of disorders related to the monocyte/macrophage lineage. The dermal dendrocyte was previously proposed as the cell of origin for JXG on the basis of Factor XIIIa reactivity, a suggestion that does not fully explain the occasional xanthogranulomatous proliferations localizing exclusively to extracutaneous sites. This study applies a panel of recently developed immunohistochemical markers to JXGs and relates the phenotype of this process to new concepts of monocyte/dendritic cell ontogeny. Twenty-seven JXG, ten dermatofibromas (DF), and ten age-matched normal skin specimens were stained using standard immunohistochemistry methods, and all JXGs were fascin+ and CD68+, although 26 of 27 were reactive for HLA-DR, 25 of 27 for Factor XIIIa, 25 of 27 for LCA, 21of 27 for CD4, and 8 of 27 for polyclonal s100. Six of those eight polyclonal S100+ cases were also reactive for monoclonal S100. None of those cases was reactive for CD1a, CD3, CD21, CD34, or CD35. Eight of ten dermatofibromas were FXIIIa+; all were negative for HLA-DR, LCA, CD4, and polyclonal s100. In controls, fascin+ dendritic cells were present but did not stain for Factor XIIIa, S100, or CD4. Based on the morphologic and phenotypic overlap of the lesional cells in JXGs and plasmacytoid monocytes, it would appear that the plasmacytoid monocyte might be considered the putative normal counterpart of the major cellular population of JXGs, a proposal that helps explain the extra-cutaneous, visceral, and soft tissue location that have been reported for occasional cases of JXG. We would also conclude that neither Factor XIIIa-nor S100+ results should preclude the diagnosis of JXG, and find that reactivity for CD4 and LCA may be used to distinguish JXG from DF when the latter is heavily lipidized or the former is not.

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