Primary pulmonary histiocytic sarcoma in dogs: A retrospective analysis of 37 cases (2000‐2015)

Abstract

Primary pulmonary histiocytic sarcoma (PHS) has been reported, but is not well characterized. The aim of this retrospective study was to describe clinical characteristics, characterize prognostic factors and report the outcome of a larger group of dogs with primary PHS. Medical records of dogs diagnosed with primary PHS at 11 institutions were retrospectively reviewed. Thirty‐seven dogs were included; 13 received CCNU‐based chemotherapy alone, 18 received surgery and adjuvant CCNU‐based chemotherapy, 3 received medical management alone and 3 dogs received surgery alone. The overall median progression free survival (PFS) and the median survival (overall survival [OS]) were 197 and 237 days, respectively. Measurable responses were noted in dogs receiving only chemotherapy; however, responses were not durable with PFS (91 days) and OS times (131 days) shorter than overall medians. Dogs that received surgery and chemotherapy had significantly prolonged PFS (276 days, P = 0.001) and OS (374 days, P = 0.001), compared with dogs not receiving surgery. As only three dogs undergoing surgery did not receive chemotherapy, it is not possible to determine the contribution of chemotherapy as an adjuvant to surgery. Dogs without evidence of intra‐thoracic metastatic disease were much more likely to undergo surgery (odds ratio = 7.04; P = 0.018). While the presence of metastasis or clinical signs at diagnosis negatively impacted PFS, only the former negatively impacted OS. These data imply that dogs presenting with PHS amenable to surgery (ie, no clinical evidence of metastasis) benefit from surgical intervention; however, the lack of a comparable surgery alone group precludes assessment of the efficacy of post‐surgical adjuvant chemotherapy.

A Contemporary Retrospective Study of Survival in Dogs With Primary Lung Tumors: 40 Cases (2005–2017)

“…Whereas, there is a clear relationship between cigarette smoking and the increased risk of developing lung cancer in people, no apparent environmental factors have been identified in dogs (10)(11)(12). The clinical signs in dogs are coughing in 50-93%, dyspnea, lethargy, anorexia, weight loss, hemoptysis, and lameness secondary to hypertrophic osteopathy or rarely metastatic lytic lesions (6,9,(13)(14)(15)(16)(17)(18). In up to 30% of cases, primary lung tumors are an incidental finding (6,9,13,16).…”

Clinical outcomes in dogs with localized splenic histiocytic sarcoma treated with splenectomy with or without adjuvant chemotherapy

“…1 Localized HS, which arises primarily from dendritic cells, is generally considered a subtype with a relatively favorable prognosis. 6 Disseminated HS, previously referred to as malignant histiocytosis, also arises primarily from dendritic cells, and is characterized by multicentric disease at diagnosis, or by the progression of LHS beyond the regional lymph nodes. 1 Disseminated HS carries a poor prognosis, potentially due to DHS being more biologically aggressive.…”

“…10,11 Dogs with LHS such as periarticular HS (PAHS) and primary pulmonary HS can have longer survival times. 6,12 Dogs with primary pulmonary HS have significantly longer survival times when treated with surgery and chemotherapy (374 days) compared to dogs that did not receive surgical treatment (131 days). 6 Localized HS can manifest in other anatomic sites including the spleen, but to date, only PAHS and primary pulmonary HS have been characterized in detail.…”

“…6,12 Dogs with primary pulmonary HS have significantly longer survival times when treated with surgery and chemotherapy (374 days) compared to dogs that did not receive surgical treatment (131 days). 6 Localized HS can manifest in other anatomic sites including the spleen, but to date, only PAHS and primary pulmonary HS have been characterized in detail. 6,12 The spleen is a common site of disease in dogs with HS, as it is frequently involved in cases of disseminated or hemophagocytic HS, with both subtypes associated with poorer prognosis.…”

“…6 Localized HS can manifest in other anatomic sites including the spleen, but to date, only PAHS and primary pulmonary HS have been characterized in detail. 6,12 The spleen is a common site of disease in dogs with HS, as it is frequently involved in cases of disseminated or hemophagocytic HS, with both subtypes associated with poorer prognosis. 4,5,7,9 LHS in dogs can also manifest in the spleen, but it is rarely reported, and thus its biological behavior is poorly understood.…”