Primary Spindle Cell Tumor of Lymph Node with “Amianthoid” Fibers: A Histological, Immunohistochemical and Ultrastructural Study

Abstract

A primary mesenchymal spindle cell tumor with amianthoid fibers was observed in an inguinal lymph node of a 70-year-old woman. With immunohistochemical stains the cells were positive for muscle actin and negative for desmin. Transmission electron microscopy (TEM) showed intracytoplasmic bundles of microfilaments with focal densities, profiles of rough endoplasmic reticulum, and basementlike material indicative of myofibroblastic and/or smooth-muscle cell differentiation. At scanning electron microscopy (SEM) the tumor was organized into slitlike spaces containing red blood cells. Amianthoid fibers showed a strong positivity for actin at their edge with a central negative core; by TEM they appeared to be formed of 200 nm thick crystallized collagen fibers surrounded by actin microfilaments arranged in a palisading fashion. The immunohistochemical and ultrastructural findings of the proliferating myoid cells suggest a possible derivation from smooth-muscle vascular cells. Collagen fiber aggregation and actin filament dismission might be secondary to anoxia due to vascular obliteration or disruption.

Intranodal Palisaded Myofibroblastoma

“…As documented by others 1,25,35 , we found aggregates of small vessels with thick mantles of hyalinized collagen merging with these structures raising the possibility that their origin is from condensation of perivascular collagen.…”

Characterization of collagen fibrils after equine suspensory ligament injury: An ultrastructural and biochemical approach

“…In contrast, normal tissue showed a regular pattern with an apparent bimodal distribution. These observations are consistent with those of other studies (Emonard et al, 1991;Jozsa et al, 1993;Tanda et al, 1993;Moeller et al, 1995;Eyden and Tzaphlidou, 2001). Very little is known about the exact mechanisms through which these abnormal collagen fibrils are formed.…”

Atypical Palisaded Myofibroblastoma of Lymph Node: Report of a rare case.

“…Because cells derived from smooth muscle usually contain desmin, the absence of desmin in palisaded myofibroblastoma initially suggested a cell type other than smooth muscle [1][2]. On the other hand, vascular or capsular smooth muscle cells could also give rise to the spindle cells of palisaded myofibroblastoma as evidenced by immunohistochemical positivity for smooth muscle actin, vimentin and myosin [7]. Though most patients present with a solitary, unilateral nodular mass, yet a single case of multicentric intranodal palisaded myofibroblastoma was reported in 1994 by Lioe TF et al [5].…”