Case series: Superficial lipomatous hamartoma in dogs and cats is a previously unreported NLCS-like dermal lesion.

In humans nevus lipomatosus cutaneous superficialis (NLCS) is a rare, benign dermal hamartoma characterized by aggregates of adipose tissue within the dermis without any connection to the subcutaneous tissue. Although NLCS is a well-recognized entity, it is considered a rare lesion with limited reports in the human literature. To date, no comparable cases have been reported in dogs and cats. Over the course of one and a half years, six cases (five in dogs, one in a cat), resembling NLCS-like lesions, were examined. In this report, we compare these cases to the human condition regarding macroscopic features, histopathology, sex, and age of the affected patients. In all cases, the dermal lesions were composed of aggregates of well-differentiated adipocytes within the dermis. Given the morphological similarity to the lesion in humans, the term "nevus lipomatosus superficialis-like lesion" might be appropriate. However, given the controversial use of the term 'nevus' in veterinary medicine and a potential for confusion with pigmented lesion, we propose the term "superficial lipomatous hamartoma" for this entity.