Case Report of a Mare Diagnosed with a Metastatic Mammary Carcinoma after the Excision of a Recurrent Intraocular Neuroepithelial Tumor.
Authors: Brocca Ginevra, Centelleghe Cinzia, Padoan Elisa, Stoppini Riccardo, Giudice Chiara, Castagnaro Massimo, Zappulli Valentina
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary A 24-year-old Irish Cob mare presented with an iris mass that was surgically removed and histologically confirmed as an undifferentiated neuroepithelial tumour; however, relapse occurred within months with evidence of squamous differentiation, followed by rapid development of widespread subcutaneous masses and subsequent neurological deterioration requiring euthanasia. Post-mortem examination and immunohistochemical analysis revealed an unexpected diagnosis of metastatic mammary carcinoma with extensive visceral, subcutaneous, and mammary gland involvement, whilst confirmatory testing of the recurrent intraocular lesion established it as a true neuroepithelial tumour relapse rather than an ocular metastasis. This represents the first documented case in equine medicine of concurrent metastatic mammary carcinoma alongside a recurrent intraocular neuroepithelial tumour, presenting a significant diagnostic challenge that required comprehensive post-mortem investigation and advanced histopathological techniques to differentiate between two distinct neoplastic processes. The case underscores the critical importance of thorough post-mortem examination and immunohistochemical evaluation when clinical presentation deviates from expected disease progression, particularly in elderly mares where multiple primary tumours may develop independently. Practitioners should maintain heightened suspicion for occult malignancy when intraocular tumours behave atypically, and recognise that mammary carcinoma in horses can present with aggressive systemic metastasis warranting careful staging and prognosis discussions with owners.
Read the full abstract on PubMed
Practical Takeaways
- •Intraocular masses in horses require careful histopathological and immunohistochemical evaluation, as concurrent systemic neoplasia may complicate diagnosis and prognosis.
- •Recurrence of intraocular neuroepithelial tumors can occur with increased biological aggressiveness; close post-operative monitoring and rapid evaluation of new clinical signs is essential.
- •Complete post mortem examination and ancillary diagnostics (IHC) should be performed in cases with unusual multi-system presentation to establish accurate diagnosis and understand disease progression.
Key Findings
- •A 24-year-old mare presented with concurrent recurrent intraocular neuroepithelial tumor and metastatic mammary carcinoma, representing the first documented case of this combination in equines.
- •The intraocular neuroepithelial tumor recurred with histological progression showing increased solid appearance and squamous differentiation within months of initial surgical resection.
- •Post mortem examination revealed widespread metastatic mammary carcinoma affecting subcutaneous tissue, multiple internal organs, and the mammary gland, requiring IHC re-evaluation to differentiate from intraocular metastasis.
- •Immunohistochemical analysis confirmed the second intraocular mass as neuroepithelial tumor relapse rather than metastatic disease, demonstrating the diagnostic importance of IHC in complex cases.