Lumps and Bumps

Subcutaneous lumps and bumps are where ultrasound beats everything that leaves the skin intact. Soft tissue planes are well defined, anatomic details can be at a submillimeter level, and what is most important to me, contrast resolution (i.e. grayscale) that relates low noise data directly to histology and histopathology of the target. I hope this recent case may illustrate some basics about the ultrasound imaging diagnostic process.

The patient was stuck from behind while riding his bicycle on a city street. He was thrown forward onto the pavement, striking his shoulder and helmet, and rolling onto his back, side, and hip. There were subcutaneous and rib bruises, gashes that required stitching, but no fractures, dislocations or central nervous system findings. About a week after the injury, the patient noticed a rock-hard bump at the edge of a black and blue mark at the top of the shoulder on the side of the trauma. The patient played tennis when he was younger, transitioning to pickleball two years previously. He did not report anything new or unusual about shoulder mobility or pain. The anonymized ultrasound image of the ‘bump’ shoots directly down into the right A-C joint, the marker is lateral (rt):

Beginning ultrasounders seem always to be playing the game of ‘name the lesion’ and most outside of Radiology do not get past that image-centric notion. Exams on patients should be patient-centric. This involves? a synthesis of 1. Everything you know about the patient at the time of the exam, 2. What are the possible forms of pathology in the region of study, independent of the presenting complaint, organized by medical urgency and seriousness, 3. The fidelity of the ultrasound equipment used in the exam for depicting regional anatomy, physiology, and pathology. When something has been identified as abnormal, and everything else has been scanned that may be pertinent, the focus shifts to more information, watchful waiting, or launching a management plan (helping a medical colleague to form his or her management plan). ‘Name the lesion’ is a teaching tool and fun at meetings, but it is rarely helpful for actual patient exams which have components of screening and the complications of comorbidities and other external factors that affect clinical presentations.

The mass fills most of the field of view. Please assume that there weren't any other relevant findings for this shoulder, like lymphadenopathy or fluid collections. The grayscale morphology appears to be patterned, which you can see because I used a low-noise, broad-band imaging device and because the grayscale was optimized for the region of interest. I feel this is an important side point because it is not always practical to adjust grayscale for an entire, large field of view. Most of the examples I see of breast cancers in postings here on Linked In show hypoechoic masses with no internal features, because the grayscale level is centered on parenchyma, not the pathologic finding.

The tissue comprising the mass is cartilage, welling up out of the AC joint and spreading laterally as a cap between bone and soft tissues. Nothing acute is going on (no effusions or tenderness) and no hint of anything invasive along any border. The architecture including micro-reflectors, is of a chronic fibrotic reaction. The important factoid is racquet sports, not the recent blunt trauma.

The next part is easy if you recall that not all cartilages are the same. Hyaline cartilage is tough, no perichondrium, no blood supply or innervation. AC joints (rib ends, symphysis pubis, and intervertebral disks) are fibro-cartilage: types 1 and 2 collagen, lots of fibrocytes, blood flow, immune cells, metabolic activity and reactivity. A check of the other A-C joint revealed a smooth rock-hard nodule (with identical ultrasound features). On questioning, the patient revealed a tiny Dupuytren’s nodule of the fourth ray of the left palm. The mass is one expression of a systemic issue of chronically stressed fibro-cartilage.

I picked an example with cartilage because this is not a tissue that gets a lot of ultrasound attention in adults. I wanted to illustrate the original form of medical ultrasound, which was its use as a physical examination tool. By the way, early professional meetings of ultrasound communities involved both physicians and nurses in multiple specialty areas. As ultrasound spread in use along with perceived doctor and nurse shortages, the general practice has tried to force this geometric peg into the round hole of an automated clinical lab procedure: great for monitoring established disease and for screening that can be protocol specified, not so good for new patients at the start of an evaluation or for preventive health. There is a great opportunity for advancing ultrasound with low-noise equipment as an interactive physical examination tool, but only if we in the field the physicians who are ultimately responsible for the use of ultrasound form definitive practice standards about what ultrasound performance and how those directives should be used for individual patient evaluations.