Chondrosarcoma of H&N

H. Ric Harnsberger, MD

Key Facts

Terminology

Definition: Malignant tumor of H&N characterized by formation of cartilaginous matrix

Imaging

CSa locations & frequency
- Larynx ≈ skull base (petrooccipital fissure) > mandible (including TMJ, masticator space) > maxilla ≈ nasal septum
Bone CT: Characteristic chondroid calcification in tumor matrix
- ˜ 50% have matrix calcification
- Chondroid calcifications described as “ring & arc” and “popcorn”
MR findings: T2 high signal, especially when calcifications not present
- If extensive calcifications, hypointensity may dominate T2 signal

Top Differential Diagnoses

Osteosarcoma of H&N
Metastasis of H&N
Non-Hodgkin lymphoma of H&N

Pathology

Classification based on histology
- Hyaline (5%), myxoid (30%), or mixed (63%)

Clinical Issues

Mean age at presentation ˜ 55 years old
Treatment: Surgical resection + radiation therapy
Disease-specific 10-year survival rates of > 90%

Diagnostic Checklist

Consider CSa as diagnosis when expansile or destructive mass of laryngeal cartilage, skull base petrooccipital fissure, mandible, maxilla, or nasal septum shows chondroid calcification

(Left) H&E shows normal cartilage

next to the increased cellularity of low-grade CSa

. Note the difference in cell size and lacunar distribution. (Courtesy L. Thompson, MD.) (Right) Clinical photograph of mandibular CSa reveals a smooth, multilobular, submucosal mass

causing significant distortion of the posterior mandibular body, resulting in teeth displacement

. Notice that the surface epithelium is intact, excluding diagnosis of retromolar trigone SCCa. (Courtesy L. Thompson, MD.)

(Left) Axial CECT reveals a large left masticator space mass with typical “popcorn” calcifications

containing both “rings & arcs.” Chondrosarcoma with visible chondroid calcifications usually indicate a lower grade tumor is present. (Right) Axial T2WI MR in the same patient shows the CSa

with characteristic pronounced T2 hyperintensity of chondroid tumors. Note bowing of the posterior wall of the maxillary sinus

along with linear low signal areas within the tumor secondary to intramural calcifications.

TERMINOLOGY

Abbreviations

Chondrosarcoma of head & neck (CSa H&N)

Definitions

Malignant tumor arising from H&N cartilage or bone characterized by formation of cartilaginous matrix by neoplastic cells

IMAGING

General Features

Best diagnostic clue
- H&N tumor demonstrating chondroid tumor matrix leads directly to radiologic diagnosis of CSa
Location
- Multiple H&N locations
  - Difficult to determine relative frequencies
- Larynx ≈ skull base (petrooccipital fissure) > mandible (including temporomandibular joint [TMJ], masticator space) > maxilla ≈ nasal septum
  - Laryngeal CSa: 72% cricoid, 20% thyroid, 8% arytenoid cartilage, hyoid bone
Size
- Variable, usually > 3 cm
Morphology
- Well-circumscribed, lobulated margins

CT Findings

CECT
- Variable, heterogeneous enhancement
- Soft tissue extension is late finding
Bone CT
- Characteristic chondroid calcification in tumor matrix
  - ˜ 50% have matrix calcification
  - Descriptive terms for chondroid calcifications include “ring & arc” & “popcorn” calcifications
- Cartilage or bone involvement by CSa variable
  - Expansion of cartilage or bone present
  - Tumor margin variable from abrupt, benign appearance to destructive margins with local invasion
    - ˜ 50% show cartilage or bone destruction