|Metastasis of a well differentiated perianal gland tumor
Fineâneedle aspirates from a perianal mass on an 8âyearâold, intact male, Miniature Poodle presenting for tenesmus showed a uniform population of wellâdifferentiated hepatoid cells with no notable criteria of malignancy. The cytologic diagnosis was a perianal gland tumor, with adenoma likely given the cytomorphology. A Standard case, the therapeutic options include surgical or hormonal castration. Is this the right decision?|
|The abdominal ultrasound revealed multiple, markedly enlarged, intraâabdominal lymph nodes.
LN aspirates also showed wellâdifferentiated polygonal, hepatoid cells displaying no notable cellular atypia.
The presence of the metastasis led to the interpretation of a wellâdifferentiated, malignant perianal gland tumor despite the benign cellular appearance.
Histopathology of the surgically excised perianal mass and one enlarged abdominal lymph node revealed lobules of uniform polygonal hepatoid cells arranged in organized islands and trabeculae surrounded by a single layer of uniform reserve cells.
Few mitotic figures were present.
The only histopathologic indication of malignancy within the primary mass was the presence of small islands of wellâdifferentiated hepatoid cells infiltrating into adjacent tissue and possible lymphatic invasion.
The histopathologic diagnosis was perianal gland adenocarcinoma.
Most textbooks describe perianal gland adenocarcinomas as showing increased cellular atypia including pleomorphism, disorganization of hepatoid cells, and increased numbers of pleomorphic reserve cells with mitotic figures.
This case is an example of the occurrence of a wellâdifferentiated perianal gland tumor with metastasis and highlights the importance of realizing that with these tumors, a benign cytologic and histologic appearance may not correlate with biologic behavior.
To the authorsâ knowledge, this is the first case reporting both the cytologic and histologic appearance of a wellâdifferentiated metastatic hepatoid gland tumor.
Source: Maggie R. McCourt Greg M. Levine Melanie A. Breshears Corey R. Wall James H. Meinkoth, Metastatic disease in a dog with a wellâdifferentiated perianal gland Tumorwellâdifferentiated perianal gland Tumor. JSAP, Early View. First published: 22 October 2018 https://doi.org/10.1111/vcp.12662
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