Cutaneous parachordoma

Abstract

Parachordomas are rare cutaneous tumors that show virtually identical histologic findings to chordomas. Therefore, the major differential diagnosis in a case of parchordoma is metastatic chordoma. Parachordomas are benign neoplasms and most often develop on the extremities adjacent to tendons, synovium or osseous structures, as opposed to chordomas, which are malignant tumors located along the craniospinal axis. While recurrences may occur in cases of parachordoma, metastases have not been reported. In this report, two cases of parachordomas are reported and the literature reviewed. By light microscopy, parachordomas show eosinophilic bands of fibrous tissue separating lobules of cells with variably vacuolated cytoplasm (physaliphorous cells) admixed with more epithelioid cells in a myxoid stroma. Parachordomas and chordomas share immunohistochemical and ultrastructural features. Both stain with S-100 protein and vimentin, and ultrastructurally both demonstrate cytoplasmic vacuoles, intermediate filaments, pinocytotic vesicles, celljunctions, and cytoplasmic membranes with microvillous processes. Chordomas more frequently express cytokeratin (98% vs. 66% in parachordomas) and epithelial membrane antigen (90% vs. 20% in parachordomas) and chordomas have a larger number of rough endoplasmic reticulum-mitochondrial complexes. Thus, positive staining with epithelial membrane antigen and the identification of a large number of rough endoplasmic reticulum-mitochondrial complexes are suggestive of metastatic chordoma. However, the definitive distinction remains a clinical one after appropriate radiologic studies of the skull and spinal chord.

Hyaline Cell-Rich Apocrine Mixed Tumor with Cytologic Atypia

“…Rhabdoid melanoma expresses melan A and HMB45 [ 11 , 12 ], and extraskeletal myxoid chondrosarcoma is positive for neuron-specific enolase and synaptophysin [ 13 ]. Parachordomas consist of epithelioid cells and physaliphorous cells (cells with vacuolated cytoplasms) [ 14 ]. Cutaneous myoepithelioma never shows ductal or syringomatous epithelial structures or cartilaginous areas [ 15 ].…”

Huge pelvic parachordoma: fine needle aspiration cytology and histological differential diagnosis

“…4 Parachordoma most often develops on the extremities adjacent to tendons, synovium or osseous structures, 5 chest wall, 6 buttocks, 7 skull, 8 hand, 9 and gastric serosa, 10 and has twice been reported in pelvis. 3,11 …”

When I use a word . . . Medical eggcorns

“…The most interesting modern examples are those in which spinal chordomas are described in the "spinal chord," of which there is one English language example. 15 In addition to these, I have also seen "Hippocrates" rendered as "hypocrites" and elsewhere "mnemonic" rendered as "pneumonic." 16 I was sorry not to have found other medical examples of eggcorns.…”

“…● There are many examples of “spinal/spermatic/umbilical chord,” partly because “chord” was an obsolete spelling of “cord”; there are 12 examples listed in PubMed from the 18th and 19th centuries. The most interesting modern examples are those in which spinal chordomas are described in the “spinal chord,” of which there is one English language example 15…”