Immunohistochemical Detection of Retinoid Receptors in Tumors from 30 Dogs Diagnosed with Cutaneous Lymphoma

Isotretinoin treatment of 12 dogs with epitheliotropic lymphoma

BACKGROUND

Epitheliotropic lymphoma is an uncommon cutaneous malignancy of T lymphocytes. Limited information is available regarding the treatment and outcome of dogs with this disease.

OBJECTIVES

To evaluate the treatment outcome and toxicity profile of isotretinoin in dogs with epitheliotropic lymphoma.

ANIMALS

Twelve dogs with a diagnosis of epitheliotropic lymphoma were included.

MATERIALS AND METHODS

A medical database was searched for dogs diagnosed with epitheliotropic lymphoma and treated with isotretinoin between 2010 and 2021. Diagnosis, treatment details and tumour response were recorded for 12 dogs.

RESULTS

All lesions resolved in four of 12 (33%) treated dogs. Lesions visibly improved in a further three dogs, giving a response rate of 58%. Two dogs' lesions remained unchanged and three progressed despite therapy. Adverse effects occurred in three dogs (25%), all of which were rapidly resolving or not affecting quality of life.

CONCLUSION

Isotretinoin treatment was a well-tolerated and effective treatment for canine epitheliotropic lymphoma.

Clinical response to isotretinoin and interferon-α of two dogs with cutaneous epitheliotropic T-cell lymphoma: a case report

BACKGROUND

There is no specific therapy for cutaneous epitheliotropic T-cell lymphoma (CETL). The administration of retinoids in conjunction with interferon-α (IFN-α) in CETL has not been reported in dogs.

CASE PRESENTATION

Two dogs (Shih tzu and Miniature pinscher) presented with multiple nodular skin lesions. Histopathological examination revealed diffuse infiltrations of lymphocytes in the epidermis and dermis, with a CD3-positive immunophenotypic profile. Based on the clinical and histopathological examination, CETL was diagnosed. Both dogs were treated with isotretinoin in combination with IFN-α and showed clinical improvement with complete or partial remission. The disease in these dogs was well-controlled for more than 264 days of overall median survival time without any additional clinical signs after initiation of the treatment. In both the cases, the dogs were followed up for 27 months, and 10 months without any evidence of recurrence or metastasis, respectively.

CONCLUSIONS

We describe the clinical efficacy of isotretinoin combined with IFN-α in 2 dogs with CETL. Long-term management with isotretinoin combined with IFN-α was effective in treating CETL in these cases.

A retrospective study of flow cytometric characterization of suspected extranodal lymphomas in dogs

Flow cytometry (FC) is widely applied to characterize and stage nodal lymphomas in dogs because it has a short turnaround time, requires minimally invasive sampling, and allows contemporary evaluation of neoplastic cells in the primary lesion and of blood and marrow involvement. We investigated advantages and limitations of FC in suspected extranodal lymphomas in dogs. The likelihood of obtaining a suitable FC sample was significantly lower for aspirates of extranodal lesions than for lymph node aspirates. However, we noted no differences among different extranodal lesion sites. We also describe FC results for 39 samples compatible with extranodal lymphoma. A dominant population of large cells was easily identified on morphologic FC scattergrams in many cases. Phenotypic aberrancies were frequently present, mainly in T-cell lymphomas. Lymphoma cells were distinguishable from normal residual lymphocytes in >85% of cases, facilitating the quantification of putative blood and marrow involvement by FC. Despite the high percentage of non-diagnostic samples (32 of 73, >40%), we support the inclusion of FC in the diagnostic workup of suspected extranodal lymphomas in dogs, in conjunction with histopathology. Histopathology is the gold standard for diagnosing lymphoma, provides relevant information, including tissue invasion and epitheliotropism, but has a longer turnaround time.

Proliferation, angiogenesis and differentiation related markers in compact and follicular-compact thyroid carcinomas in dogs

Immunohistochemical markers (IGF-1, IGF-1R, VEGF, FGF-2, RARα and RXR) were evaluated in healthy canine thyroid glands (n=8) and in follicular-compact (n=8) and compact thyroid carcinomas (n=8). IGF-1, IGF-1R and VEGF expression was higher in fibroblasts and endothelial cells of compact carcinoma than in healthy glands (P < 0.05). Compared to follicular-compact carcinoma, compact carcinoma had higher IGF-1R expression in fibroblasts, and higher FGF-2 expression in endothelial cells (P < 0.05). RARα expression was higher in endothelial cells of compact carcinoma than in those of other groups (P < 0.05). The upregulation of these proliferation- and angiogenesis-related factors in endothelial cells and/or fibroblasts and not in follicular cells of compact carcinoma compared to healthy glands supports the relevance of stromal cells in cancer progression.

Post-surgical treatment of thyroid carcinoma in dogs with retinoic acid 9 cis improves patient outcome

The objective of the present study was to compare the effects of isotretinoin 9-cis (RA9-cis) as a post-surgery treatment of thyroid carcinoma to a traditional treatment (doxorubicin) and no treatment. Owners who did not want their dogs to receive treatment were placed into the control group A (GA; n=10). The remaining dogs were randomly placed into either group B (GB; n=12) and received doxorubicin at a dose of 30 mg/m² every three weeks, for six complete cycles or group C (GC; n=15) and treated with RA9-cis at a dose of 2 mg/kg/day for 6 months. The time of the recurrence was significantly shorter in the GA and GB compared to GC (P=0.0007; P=0.0015 respectively), while we did not detect differences between GA and GB. The hazard ratio of recurrence between GA and GB compared to GC were 7.25 and 5.60 times shorter, respectively. We did not detect any differences between the other groups. The risk ratio of recurrence was 2.0 times higher in GA compared to GC and 2.1 times higher in GB compared to GC. The type of carcinoma had an effect on time of survival with follicular carcinomas having an increased mean survival time than follicular-compact carcinomas (P<0.0001) and follicular-compact carcinomas had a longer mean survival time than compact carcinomas. The interaction among treatment and type was significant, but survival time in follicular carcinomas did not differ between treatments. In follicular-compact carcinomas the survival time of GC was greater than GB (P<0.05), but we did not detect a difference between GA and GB. In conclusion, this study shows that the use of surgery in combination with RA9-cis treatment significantly increases survival rate and decreases the time to tumor recurrence when compared to doxorubicin treated or untreated dogs. The histological type of carcinoma interacted with treatment for time to recurrence and survival time, with more undifferentiated carcinomas having a worse prognosis than differentiated carcinomas.

Advances in the management of skin cancer

Skin cancer is one of the most commonly diagnosed cancers in the world today in both humans and our pet population. Advances in molecular techniques are now affording us an opportunity to develop therapeutics targeted at specific cancer-related cellular pathways. However, despite progress in conventional treatments, such as chemotherapy and radiation, and the new targeted therapies, some cancers, such as melanoma and cutaneous lymphoma, continue to cause significant mortality and morbidity. This short synopsis is not complete but is aimed at providing an insight into current advanced treatments and horizon therapies for cutaneous malignancies in dogs and cats with comparative aspects.