ERBB2 and metastatic carcinoma: This case underscores several diagnostic challenges: (1) histology from the primary lesion initially suggested a benign tumour, discordant with aggressive radiological features; (2) ancillary molecular testing with PLAG1 FISH was critical in linking the primary PA with metastatic carcinoma; and (3) HER2 overexpression and androgen receptor positivity highlighted potential therapeutic targets, though the rapid disease course precluded treatment.