Mediastinal histiocytic sarcoma with abdominal metastasis in a Somali cat

Abstract

A nine–year-old female neutered Somali cat presented with a one-month history of weight loss and inappetance. Thoracic radiographs revealed an extensive cranial mediastinal mass, and fine needle aspirate cytology and core needle biopsies were initially suggestive of a thymoma. The mass was excised via a mid-ine sternotomy and partial pericardectomy. Clinical signs recurred four weeks postsurgery and investigations revealed recurrence of a mediastinal mass, pleural effusion and an additional small mass cranial to the right kidney. Histopathological examination and immunohistochemistry of the previously resected mass prompted a revised diagnosis of histiocytic sarcoma (HS) with abdominal metastasis. The cat was treated with doxorubicin and lomustine but did not respond well and was euthanased two months later. HS is an uncommon neoplasm in cats with only two cases of mediastinal involvement reported in the literature. This case underlines the importance of immunohistochemistry in the evaluation of mediastinal masses.

Periarticular histiocytic sarcoma with heart metastasis in a cat

“…1,2 In cats, reported primary sites include the nasal cavity, eye, spleen, brain, trachea, mediastinum, femur, tarsus, skin, periarticular tissues, and vertebral canal. [4][5][6][7][8][9][10][11][12][13][14] In the present case, HS appears to have originally arisen from the left forelimb involving the metacarpal, carpal, radial, and ulnar bones. In cats, localized HS typically progresses rapidly.…”

“…1,2 Reported metastatic sites of feline HS include lungs, liver, skin, bone marrow, LNs (peripheral, intra-abdominal and thoracic), brain, and kidney. [7][8][9]11,13,15 Heart metastasis have not been previously reported. Even in other species, secondary cardiac involvement with HS represents an exceptionally unusual condition, with only a few case reports published in dogs [16][17][18][19] and people.…”

“…1,2 Histiocytic sarcomas are rare, malignant, and aggressive neoplasms that carry a poor prognosis in cats. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Histiocytic sarcomas that originate at a single tissue site or in a single organ (with solitary or multiple foci) are referred to as localized HS. 1,2 In cats, reported primary sites include the nasal cavity, eye, spleen, brain, trachea, mediastinum, femur, tarsus, skin, periarticular tissues, and vertebral canal.…”

Primary histiocytic sarcoma in the brain with renal metastasis causing internal ophthalmoparesis and external ophthalmoplegia in a Maine Coon cat

“…Feline HS is a rare neoplastic process that can affect several locations, [1][2][3][4][5][6][7][8][9][10] including the central nervous system (CNS). To date, only four feline cases of CNS HS have been described.…”

“…11 MHCII (antigen-presenting cell marker) positivity is consistent with histiocytic disease, but its use had not been described in CNS feline HS, although it is used in this disease in feline patients. 2,4,6 Different genetic mutations have been found in people presenting with CNS HS through genomic sequencing, including PDGRF, 18 BRAF V600E 30 and PTPN11 mutations. Recently, in dogs with non-CNS HS, the PTPN11 mutation has also been identified, 31,32 as has a mutation on KRAS.…”