Incipient chordoma: a report of two cases of early-stage chordoma arising from benign notochordal cell tumors

Abstract

Chordomas are rare malignant bone tumors primarily involving both ends of the axial skeleton that present as destructive bone lesions with a large soft tissue mass. Chordomas were previously believed to arise from notochordal remnants. However, recent studies suggest the possibility that chordomas arise from benign notochordal cell tumors. We present two cases of coccygeal incipient chordoma that strengthen the new hypothesis. The first case was an 83-year-old man who died of prostatic adenocarcinoma. The second case was a 79-year-old man who died of hepatocellular carcinoma. The coccygeal tumors were composed of intraosseous and extraosseous infiltrative lesions. The intraosseous lesions consisted of both benign notochordal cell tumor and incipient chordoma. The extraosseous lesions were consistent with incipient chordoma. In addition, two other small benign notochordal cell tumors were found at a different level in case 1. It is conceivable that pre-existing intraosseous benign notochordal cell tumors transform into incipient chordoma and then extend through the cortex into the surrounding soft tissue. The incidence of incipient chordoma appears much higher than expected because chordomas are rare tumors with an incidence of one case per 1 000 000 persons per year. We suspect that unknown factors transform incipient chordoma into classic chordoma.

Case Report: An Unusual Osseous Lesion

“…One report from 2002, do describe a chordoma observed adjacent to a benign notochordal lesion in the coccyx occurring concomitant with two BNCTs in the sacrum [1]. In 2005, a report was published describing two cases with BNCTs associated with miniature chordomas (incipient chordomas) [16]. Finally, one study (2007) identified BNCTs in 7.3% (6 of 82) of sacral/coccygeal resections performed for chordoma [11].…”

Transrectal EUS-guided FNA biopsy of a presacral chordoma-report of a case and review of the literature

“…However, this theory has recently been challenged by Yamaguchi et al who proposed that chordomas instead arise from benign notochordal cell tumors [2] . The microscopic hallmark of these tumors is the presence of characteristic large cells with numerous cytoplasmic vacuoles known as physaliphorous (Greek: droplet bearing) cells.…”

Solitary lymph node metastasis without local recurrence of primary chordoma

“…Both cell groups are arranged in band-like formations circumscribed by basophylic, mixoid stroma [22]. Mytoses are rare and not necessarily pathologic [28].…”

“…It accounts for approximately 3-4% of primary bone tumors and is localized along the axial skeleton [6,22,28]. This tumor develops predominantly in the sacrococcygeal (50%), spheno-occipital (35%) and cervical (15%) region and is generally regarded as a locally aggressive tumor with slow progression growth rate and metastatic incidence ranging from 5 to 40% [5,20].…”

“…This tumor has a strong positivity to vimentin (VIM), CK AE1/AE3 (pan-keratin), S-100 protein, epithelial membrane antigen (EMA) and CK (cyto-keratin) with low molecular weight [15,21,28].…”