Vetdle

Think. Diagnose. Play.

Vetdle Archive

Archive Case #199: Canine Cutaneous Histiocytoma

Dog veterinary case - Medium - September 18, 2026

Clinical Clues

  1. Within a few weeks, a young dog develops a round pink nodule on the pinna.
  2. The skin mass appeared rapidly rather than enlarging over many months.
  3. The mass is hairless, button-like, and slightly ulcerated from rubbing.
  4. The dog is otherwise bright and not bothered by it.
  5. Cytology supports a benign round cell tumour of young dogs.
  6. A cutaneous histiocytoma is a common spontaneously regressing skin tumour in young dogs.

Diagnosis

Canine Cutaneous Histiocytoma

This case is most consistent with Canine Cutaneous Histiocytoma because the dog has a rapidly appearing button-like skin mass with a classic young-dog signalment. The most important clues are the solitary pink nodule and benign round-cell cytology, which make mast cell tumour less likely.

Learning review

Review the case evidence

Use the paired clues to explain how the evidence in this dog case supports the provided diagnosis, Canine Cutaneous Histiocytoma, then compare your reasoning with the case explanation.

Evidence checkpoints

Clues 1-2

  1. Clue 1: Within a few weeks, a young dog develops a round pink nodule on the pinna.
  2. Clue 2: The skin mass appeared rapidly rather than enlarging over many months.

Clues 3-4

  1. Clue 3: The mass is hairless, button-like, and slightly ulcerated from rubbing.
  2. Clue 4: The dog is otherwise bright and not bothered by it.

Clues 5-6

  1. Clue 5: Cytology supports a benign round cell tumour of young dogs.
  2. Clue 6: A cutaneous histiocytoma is a common spontaneously regressing skin tumour in young dogs.

Self-review prompts

  1. After clues 1-2, what evidence from this dog case shaped your initial interpretation?
  2. When you compare clues 3-4 with clues 1-2, what changed in your reasoning about Canine Cutaneous Histiocytoma?
  3. How do clues 5-6 align with the case explanation for Canine Cutaneous Histiocytoma?

Educational Use

Vetdle archive cases are educational veterinary games for diagnostic reasoning practice. They do not provide veterinary advice, diagnosis, treatment, or professional medical guidance.