Clinicopathological Evaluation of Clear Cell Hidradenoma (Acrospiroma) Within Multiple Tumor Complex in a Dog

Abstract

Background: Clear cell hidradenoma (acrospiroma) is adnexal tumors that arise from the distal excretory duct of eccrine sweat glands. It is generally defined in humanbeings. It presents solitary structure in firmness nodule. Most frequently are encountered in head, face, and upper extremities in humans. Hidradenomas are called generally by definition benign. Their malignant transformations and metastasis are seen very rarely. In veterinary literature database, the malignant form of tumor has been defined as an unique report in four dogs. They are extremely rare tumors in dogs. It is not documented within multiple tumor complex up to now.Case: In the case, three tumors were detected in a 9-year-old neutered female German shepherd dog. After clinical examination, a complete surgical resection of all masses was performed and masses were sent to Pathology for diagnosis. A mass on the right last rib was a 8x6 cm in diameters with severe ulceration. The mass had a hard texture, immobility and irregular borders. Other masses were localized on the back and left caudo-abdominal mammary lobe. Tumors on the back and the mammary lobe did not invade muscle layer, but the tumor on the last rib aggressively invaded surrounding tissue and were very difficult to remove surgically After macroscopy, all the masses were stained with hematoxylin-eosin (H&E), Mayer’s mucicarmine and Periodic Acid Shiff (PAS) stainings. In the first mass, there were multilobular epithelial islands between prominent fibrous septa from the upper to deep of dermis. The neoplastic cells were generally round or polyhedral in shape. Some of cytoplasms were eosinophilic at different degree. But cytoplasms were generally finely granular and vesicular or clear in appearance. Some cells had possible glycogen deposits. Nucleus was oval to round and had fine reticular chromatin and a distinct nucleolus. The tumor was diagnosed as clear cell hidradenoma. Others were was belonged to hemangioma on the back and malignant mixed tumor in the mammary gland.Discussion: In our case, two cell types having benign characteristics were also noted. Some clear cells contained PAS (+) material showing glycogen deposits. Additionally, there were some fibrous septa separating those cell islands. Thus, it is thought that the histopathology shows parallelism to many reports described in human beigns. Clear cell hidradenoma described in this case is first documentation as benign counterpart on the basis of veterinary literatures even though a previous report including clear cell hidradenocarcinoma in four dogs. And also, it has been reported to be very rarely seen tumor in human beings. However, any hormonies in terms of its predilection site can not be found among the cases with clear cell hidradenoma in human counterparts, because the tumor is encountered at skin of last right rib. This situation has shown us the tumor does not select any predilection site as described in this case. It has been understood on the basis of literatures that this is the first case report of describing benign tumor of ecrine sweat duct in dogs. Also, there has been no any documentation regarding in this multiple tumor complex