THE DETECTION OF MELANOMA RECURRENCE BY AN ULTRASOUND SURVEILLANCE SCAN
Roisin Costigan, University College Dublin
Background:
There is a high incidence of melanoma reoccurring within the first 5 years after initial diagnosis. Regular surveillance imaging is key for the survival of these patients. As a result of recent research, ultrasound now plays a role in the detection of recurrence. The area specifically scrutinized by ultrasound is the lymphatic nodal basin near the previous primary site of cancer. Ultrasound has been proven to be more accurate in the detection of abnormal lymph nodes compared to other modalities.
A 56-year old man was diagnosed with stage IIIC melanoma. A wide local excision and sentinel node biopsy was performed which was positive. As a result, CT and ultrasound scans were performed at regular intervals after diagnosis and staging.
Ultrasound findings:
The first ultrasound scan performed 4 months post-diagnosis was normal. However, 8 months post-diagnosis, an abnormal lymph node was detected on ultrasound. This lymph node had suspicious features indicating malignancy. CT identified this atypical lymph node also and showed prominent mesenteric lymph nodes concerning for metastasis. A biopsy was performed on the node detected by ultrasound which confirmed the return of metastatic malignant melanoma.
Discussion:
Despite the excellent accuracy of ultrasound in detecting melanoma recurrence at the nodal basin, this service is only available in two hospitals in the Republic of Ireland. There are a number of barriers which inhibit its availability including the lack of specialised training and doubt regarding the need if regular cross-sectional imaging is performed.
Conclusion:
This case demonstrates how sensitive and specific ultrasound can be in identifying abnormal lymph nodes suspicious of metastatic melanoma recurrence. However, accuracy depends on the sonographer’s skill. Hence, more training must be provided in order to make this service available at more clinical sites.