Canine cutaneous histiocytoma is a common benign skin tumor in dogs, accounting for 6.7%-14% of canine skin tumors. Clinically, it is usually solitary, occasionally multiple, and is generally diagnosed based on the dog’s age, symptoms, biological manifestations of cancer, and cytological examination. The tumor grows fast, but it is a benign tumor that usually regresses within 2-4 months and rarely recurs. Surgical resection may be considered if cancer affects the dog’s daily behavior.
This article is a case analysis of the diagnosis and treatment of canine foot skin histiocytoma as follows:
1: Case information
2.Breed: Golden Retriever
3.Age: 1.2 years old
5.Diagnosis time: 2022.8.15
2: Medical history investigation
1.Visiting problem: There is swelling, redness, slight ulceration, and frequent licking on the left hind limb
2.Main statement: During this week, the dog was found to lick his feet frequently and walk with a little limp, and swelling was found in the foot examination. The owner disinfected it with iodophor at home and put an Elizabethan ring on it, but there was no noticeable improvement. The condition has been half a month, and the spirit, appetite, and bowel movements are regular, and the activities and activities outside are also typical. There are occasional limps at home, and the annual vaccination has been completed. Deworm on time.
3: Physical Examination
1. Overall inspection
BCS: 5/9, good body condition, smooth fur, no dander, normal limbs and bones, and a skin tumor on the left hind limb.
2. General inspection
BW: 32KG T: 38.8℃ HR: 120/min RR: 30/min
3. System check
Auscultation of heart and lung sounds is normal, palpation of the abdomen is normal, and foot resistance is checked.
4: Laboratory tests
Inspection items: blood routine, acute reaction protein, skin cytology examination, biochemical examination
Acute Response Protein
Microscopic examination of skin cytology
Blood routine was normal, acute reaction protein was slightly elevated, skin cytology suggested histiocytoma, and biochemical liver and kidney indicators were normal.
Pictures of affected areas
5: Diagnosis and Treatment
Diagnosis: Canine Histiocytoma
Treatment: Surgical resection (affects normal behavior and activities and is prone to secondary infection, so surgical resection is recommended)
1.1 Basic preparation before surgery and essential physical examination to assess risk
Shave the affected area after anesthesia, rinse with normal saline, and then perform normal surgery disinfection
1.2 Medication after surgery
Amoxicillin Clavulanate Potassium 1.6ML Subcutaneous injection once a day for five consecutive days.
Kelu Wound Spray 2-3 times a day. Clean the wound first and then apply the gel.
Kelu gel 2-3 times a day
1. Canine cutaneous histiocytoma is a relatively common benign tumor. Although it often occurs in young dogs, histiocytoma should also be checked for skin tumors in middle-aged and elderly animals.
2. In cytology, histiocytoma, and plasmacytoma are easily confused around cell tumors. Comprehensive analysis should be based on essential physical examination and medical history symptoms.
3. When communicating with the owner, it is necessary to leave a certain amount of leeway. Puncture cytology is not the standard for diagnosing tumors, and the pathology of the submitted histopathology shall prevail.
4. When some histiocytes mixed with small lymphocytes appear in cytology, it means that histiocytoma may be about to regress on its own.
5. It is necessary to restrict exercise after the operation and keep the breeding environment dry and clean to avoid surgical wound contamination.
6. During the hospitalization period, the assistant must regularly check whether the Elizabeth ring has fallen off to avoid secondary infection caused by the dog licking the wound.
7. After surgical resection, it is necessary to take medication and clean the wound on time.
8. Remove the stitches within one week.
One week after hospitalization, the stitches were removed from the wound, the wound healed well, the walking was expected, the appetite and defecation were normal, and the prognosis was good.
8: Disease pathogenesis and prevention
Histiocytes are CD34+ stem cell-derived cells that differentiate into antigen-presenting cells (dendritic cell lineage) or phagocytic cells (monocyte/macrophage lineage). Disorder in these cell lines can lead to various reactive and neoplastic conditions in humans, dogs, and cats. Among them, canine cutaneous histiocytoma is a common benign skin tumor in dogs derived from Langerhans cells, an epidermal antigen-presenting cell. It accounts for 6.7% to 14% of all skin tumors in dogs. Canine dermal histiocytoma mainly presents as a red, hairless, nodular solitary lesion protruding from the skin, some with a typical “button” appearance, which may sometimes be ruptured and ulcerated. Usually, it does not cause other obvious clinical symptoms. In clinical practice, fine-needle aspiration of tumors is generally carried out for cytological examination. Microscopic examination will show flakes of light blue basophilic protein background and round cells of various sizes. The cytoplasm is mildly basophilic and nonvacuolated, and the nuclei are eccentric, oval, or reniform. Generally, canine dermal histiocytoma cells have the same appearance and few malignant cytological features. However, due to their rapid growth rate, the mitotic index may be high, and the division is apparent. It should be interpreted carefully to avoid misjudging it as a malignant tumor. Canine dermal histiocytoma can occur in dogs of any age. Still, it is more common in young dogs under three years old, and most of them will resolve spontaneously within 2-4 months without appropriate treatment or surgery. The prognosis is good. However, clinically, histiocytoma has a unique growth site and affects normal behavior and activities. Surgical resection is recommended for pet owners. Usually, surgical resection also has a good prognosis.
Prevention: There is no prevention method, and the factors affecting the regression of canine cutaneous histiocytoma are still unclear. There are two conjectures. One is that its spontaneous regression is mediated by CD8+αβT cells. Reversal is accompanied by progressive infiltration of lymphocytes, which eventually spread throughout the lesion, and these lymphocytes may be crucial to tumor cell lysis. Another hypothesis is that since histiocytoma is a tumor with a small amount of fibrovascular stroma, disruption of tumor vascularization may make tumor cell survival difficult, so induction of tumor necrosis may be a potential mechanism leading to tumor regression.
Furthermore, the natural regression of tumors in humans and animals is often attributed to a reduction in tumor cell proliferation, induction of apoptosis, or activation of the immune system. It has been found that the regression of canine histiocytoma may also be the result of an imbalance between cell proliferation and programmed cell death. Still, the current understanding of its regression remains limited.
In conclusion, canine cutaneous histiocytoma has the characteristics of self-regression. It is a benign tumor frequently occurring in young dogs under three years old and generally does not cause obvious clinical symptoms in dogs. Therefore, a cytological examination is used to confirm the tumor histiocytoma, and then the changes in the tumor can be observed. Depending on the dog’s condition, it can be decided whether surgical resection is required and whether unnecessary treatment should be avoided.