Metastatic Adenoid Cystic Carcinoma with Signet Ring Morphology in the Liver: Detection of MYB Translocation in Adenoid Cystic Carcinoma - Abstract
Adenoid cystic carcinoma (ACC) is a relatively rare salivary gland malignancy. Approximately 25-55% of patients with ACC develop distant metastases. We present the case of a 65-year-old female who was incidentally found to have a hepatic lesion while undergoing monitoring for an intraductal papillary mucinous neoplasm of the pancreas. Significant background history included a previously resected ACC of the right sublingual gland with adjuvant radiotherapy seven years prior and Hepatitis B positive serology. Radiology review at the hepatobiliary oncology multidisciplinary meeting favoured a cholangiocarcinoma and a hemi-hepatectomy was performed. Macroscopic examination of the left hemi-hepatectomy specimen demonstrated a well-defined firm pale lesion in segment 2/4a. The histologic examination of this area showed a relatively well-demarcated lesion comprising of tubules and cords with a biphasic basaloid appearance and basement membrane matrix production. Large areas with signet ring morphology were also seen. The morphologic features and the presence
of myoepithelial cells as demonstrated by immunohistochemical staining for S100, p63 and SMMHC were suggestive of a metastatic salivary gland tumour. Cribriform architecture typical of adenoid cystic cell carcinoma was not present. The histologic sections of the primary sublingual lesion were reviewed. These demonstrated typical cribriform architecture of adenoid cystic carcinoma with focal signet ring morphology. Fluorescent in situ hybridization (FISH) studies performed on both the primary and the metastatic lesion demonstrated MYB translocation, confirming the diagnosis and thus further augmenting the diagnostic accuracy. This case highlights the value of recent advances in molecular testing and their role in diagnosis of cases with unusual morphologic features.