Cutaneous histiocytoma (CH) is a very common benign neoplasm of young dogs, but multiple cutaneous histiocytomas (MCH) have rarely been encountered in dogs and have mainly been reported in Shar-pei breeds. Since the clinical prognosis of the disease is different from CH, MCH is found similar to cutaneous Langerhans cell histiocytosis (LCH) in humans. This case report presents lomustine treatment in a dog with MCH.
A 1-year-old, Rottweiler, neutered female dog was presented to the clinic with multiple cutaneous lesions, high fever, lethargy and anorexia. Skin biopsies were obtained from the right hindlimb for histopathological examination and were placed into the %4 formaldehyde solution for 24h. After the tissue specimens were routinely processed, they were embedded into paraffin blocks. 4-5 µm tissue sections were cut and stained with Hematoxylin and Eosin staining. In addition, immunohistochemistry (IHC) was performed for CD1a expression. Treatment was first carried out with the use of ciclosporin 5 mg/kg (PO) once daily. However, recurrence of the lesions was observed as the dose of the corticosteroids was tried to be reduced. So that lomustine 90 mg/m2 (PO) was given the dog as indicated previously (1).
Macroscopic
findings: Skin lesions located on the right hindlimb are progressive, ulcerative, erythematous and button-like multinodular massed ranged between 0.5 to 2 cm in diameter (Figure 1).
Histopathology revealed nonencapsulated, densely cellular composition of histiocytic cells, which were arranged in sheets (Figure 2, 3). There was also severe inflammation characterized by neutrophil leukocyte infiltration. In addition, in some areas there were randomly distributed, significant immunopositive cells for CD1a expression (Figure 4).
Discussion:
MCH is an uncommon, progressive disease of dogs. There are very few reports on MCH, which are both in wide age range and in different species. This syndrome of multiple, persistent and recurrent MCH can be documented under LCH, as the condition LCH in humans2. In one study, histiocytic cells were found to originate from Langerhans cells. There is no difference in the immunophenotypic features of the CH and LCH, and CD1a can be used for the detection of histiocytic diseases. Likewise, CD1a was found positive in this case and was found compatible with the MCH, as well as LCH. The positive effect of lomustine on histiocytic tumors has been previously reported for the treatment of MCH. In this case, effective treatment could not be obtained with corticosteroids. So that treatment was continued with lomustine and its successful effect was confirmed in the treatment of MCH.
