A pilot study demonstrating the efficacy of transcutaneous bilirubin meters to quantitatively differentiate contusions from Congenital Dermal Melanocytosis

Abstract

Objective: Congenital Dermal Melanocytosis (CDM) can be difficult to differentiate from contusions. The need for a prompt and accurate diagnosis is best illustrated in cases where child abuse and maltreatment is of concern. Transcutaneous bilirubin (TCB) spectrophotometry has been well established to measure bilirubin under the skin for jaundice in infants. The use of TCB spectrometry has not been used to identify or differentiate contusions from CDM. We hypothesized that bilirubin, a degradation product of hemoglobin, would be elevated in contusions but not in CDM thus demonstrating the efficacy of a novel diagnostic technique to compliment or improve on physical assessment alone.

Methods: Pilot study with thirty-seven infants and children noted to have CDM and fifty-six infants, children and adults with contusions underwent measurement of their lesion with TCB spectrometry. In each patient, the affected skin was scanned along with the adjacent unaffected native skin allowing an internal control for individual pigment variation.

Results: TCB measurements of CDM resulted in lower transcutaneous bilirubin values that were not significantly different from adjacent native skin pigmentation. This was in contrast to cutaneous contusions, which resulted in a higher measured value (mean 5.01 mg/dL) compared to adjacent native tissue (1.24 mg/dL) demonstrating a four-fold increase in measurement at the lesion site (P < 0.001). Direct comparison of a ΔTCB value (lesion measurement minus the adjacent tissue) demonstrated a significantly higher value in contusions compared to CDM with a mean value of 3.77 and 0.12 mg/dL, respectively (P < 0.001).

Conclusions: TCB Spectrometry as a novel diagnostic technique has the potential to discern contusions from CDM and may therefore have the ability to compliment the use of physical assessment alone.

Keywords: Bruise; Congenital Dermal Melanocytosis; Contusion; Non-accidental trauma; Pediatric abuse; Pediatric maltreatment; TCB.