Pulmonary adenocarcinoma with osteoblastic bone metastases in a cat

Feline pulmonary carcinoma: Gross, histological, metastatic, and immunohistochemical aspects

Feline pulmonary carcinoma (FPC) is an uncommon neoplasm with unique morphological features. We describe the gross, histological, metastatic, and immunohistochemical aspects of FPC, based on postmortem examinations from an 11-year retrospective study. Thirty-nine cases were selected. Predispositions were observed in senior (P < .001) and Persian (P = .039) cats. There were three gross patterns of the pulmonary tumors: (a) a large nodule and additional smaller nodules, (b) a solitary nodule, and (c) small, multifocal to coalescent nodules. Extrapulmonary metastases were present in 22/39 cases (56.4%), mainly in the regional lymph nodes (17/39, 43.5%), skeletal muscles (9/39, 23%), kidneys (6/39, 15.3%), and parietal pleura (4/39, 10.2%). The primary tumor size was correlated with the occurrence of extrapulmonary metastases (P = .002). Histologically, the tumors were classified as papillary adenocarcinoma (19/39, 48.7%), adenosquamous carcinoma (ADS) (8/39, 20.5%), acinar adenocarcinoma (6/39, 15.3%), solid adenocarcinoma (3/39, 7.6%), lepidic adenocarcinoma (2/39, 5.1%), and micropapillary adenocarcinoma (1/39, 2.5%). By immunohistochemistry, 39/39 cases (100%) were positive for pancytokeratin, 34/39 (87.1%) for thyroid transcription factor-1, and 8/39 (20.5%) for vimentin. Immunoreactivity for p40 was detected in the squamous component of all ADSs (8/8, 100%) and occasionally in the glandular component of adenocarcinomas (10/31, 32.2%). Napsin A expression was absent in all feline tissue tested. The results indicate that a modified and simplified histological classification based on current human and domestic animal systems is appropriate for cats. Additionally, this study highlights the utility of p40 as an immunohistochemical marker for the diagnosis of FPC with squamous differentiation.

Tolerability and outcome of palliative treatment for metastatic pulmonary carcinoma in cats

OBJECTIVES

Pulmonary carcinoma is uncommon in cats and reporting of outcomes following medical treatment is limited, especially in presence of metastases. The aim of this study was to describe the outcome of cats affected by metastatic primary pulmonary carcinoma and to evaluate the tolerability of palliative treatment in this patient population.

MATERIALS AND METHODS

Medical records were searched for cats with a cytological or histopathological diagnosis of primary pulmonary carcinoma and evidence of metastatic disease. Cats were treated with antineoplastic agents, corticosteroids, non-steroidal anti-inflammatory drugs (NSAIDs) or received no systemic treatment. Cases in which thoracic CT was not performed, and those lacking definitive diagnosis by cytology or histopathology or receiving curative-intent surgery were excluded.

RESULTS

Thirty-four cats were identified: 18 were treated with antineoplastic agents and 16 received corticosteroids, NSAIDs or no treatment. Presenting clinical signs included coughing (53%), tachypnoea (26%), gastrointestinal signs (35%) and lethargy (18%). CT scan identified metastases to the lung parenchyma in all cases and additional metastatic lesions in 10 of 34 (59%) cases; pleural effusion was detected in 11 cases (32%). The overall median survival time for all cats was 64 days [range 1-1352 days; 95% confidence interval (CI) 48-164]. Presence of respiratory signs at presentation was the only factor influencing survival in the multivariable analysis.

CLINICAL SIGNIFICANCE

Medical treatment was well tolerated and appeared to palliate clinical signs in cats with metastatic pulmonary carcinoma, albeit with a modest duration and short overall survival. The role and benefit of chemotherapy/antineoplastic agents versus conventional palliative drugs in this setting remains unclear.

Metastatic pulmonary carcinomas in cats ('feline lung-digit syndrome'): further variations on a theme

CASE SERIES SUMMARY

The aim of this retrospective case series was to describe seven cases where cats with primary lung tumours were presented because of metastases to extra-pulmonary sites ('feline lung-digit syndrome'). Specifically, we wanted to emphasise less typical case descriptions where tumour emboli resulted in lesions developing in the musculature (including the muscles of the head), skin or distal aorta.

RELEVANCE AND NOVEL INFORMATION

The cases are presented to increase clinical awareness of this entity in feline practice, especially when characteristic combinations of clinical signs are present. When clinicians have a high index of suspicion for these presentations, radiology (thorax and digits) or ultrasound (distal aorta), combined with collection of fine needle aspirate specimens for cytology, are usually sufficient to secure a definitive diagnosis. Novel information in this series includes CT and MRI findings from some cases. Typically, needle aspiration or biopsy targeting the skin, digits and lesions in musculature is far easier compared with sampling the primary tumour site in the lungs. The differential diagnosis and investigation of multiple digital lesions is also considered.

Outcome and prognostic indicators in 20 cats with surgically treated primary lung tumors

The purpose of this retrospective study of 20 client-owned cats was to describe the clinical signs, surgical interventions, histological features, stage and treatments of primary lung tumors removed by surgical excision, and to determine which factors significantly influence survival. Any cat that underwent surgical resection of a primary lung tumor between 2000 and 2007 was included in the study. Patient records were reviewed and signalment, clinical signs, preoperative diagnostics, surgical findings and histopathological results recorded. Histological reports were reviewed and scored using World Health Organization criteria. The Kaplan-Meier test was used to evaluate each potential prognostic factor with survival. Twenty cats met the inclusion criteria. The presence of clinical signs (such as dyspnea) at the time of diagnosis (P = 0.032), pleural effusion (P = 0.046), stage M1 (P = 0.015), and moderately and poorly differentiated tumors on histopathology (P = 0.011) were factors that were significantly correlated with reduced survival times. The median survival time of the 20 cats was 11 days. Cats presenting with no clinical signs had a median survival time of 578 days post-surgery vs 4 days post-surgery when presented with clinical signs. Cats staged T1N0M0 lived longer than cats at other stages (P = 0.044). Of the cats that survived to the time of suture removal, median survival time was 64 days. The results indicate that the presence of clinical signs, pleural effusion, moderately and poorly differentiated tumors on histopathology, evidence of metastasis and any stage beyond T1N0M0 are negative prognostic indicators for cats with primary lung tumors. The findings demonstrate that cats that presented with clinical signs, pleural effusion, any stage other than T1N0M0, or moderately and poorly differentiated tumors on histopathology had a poor prognosis. Therefore, extensive preoperative diagnostics, including computed tomography scans, should be performed before considering surgical intervention in these cats. These findings may be used to guide therapeutic decision-making in cats diagnosed with primary lung tumors.

Unusual rib metastasis in two cats with pulmonary carcinoma

Two cats had chronic respiratory signs associated with pulmonary carcinoma. In each case, computed tomography demonstrated similar pulmonary masses, pleural fluid and osteolytic expansile rib lesions as a result of local costal spread. This is the first report of feline primary pulmonary adenocarcinoma with local spread to the ribs, causing osteolysis. Although pleural involvement is common with this neoplasm, local spread to ribs is rarely reported.

Metastatic carcinoma in the ulna of a cat secondary to a suspected pulmonary tumour

A 14-year-old male neutered Burmese cat presented for investigation of right fore limb lameness that was non-responsive to anti-inflammatory drugs and opioids. Thoracic radiography showed multiple pulmonary soft tissue nodules and a larger cavitated mass. Right elbow radiographs revealed marked peri-articular proliferation of new bone and periosteal reaction primarily affecting the ulna. Histopathological examination of an incisional biopsy of the right ulna revealed neoplastic proliferation of epithelial cells; this was confirmed as a poorly differentiated carcinoma with immunohistochemistry. Amputation of the right fore limb was performed at the owner's request. After surgery, radiographs of the limb showed progression of bone proliferation. Repeat pathological analysis confirmed a metastatic carcinoma. The cat deteriorated 3 days after surgery and was euthanased a week later as a result of severe respiratory distress. This case represents an unusual case of metastasis of a suspected primary lung tumour to the ulna in a Burmese cat.

Feline lung-digit syndrome: unusual metastatic patterns of primary lung tumours in cats

PRACTICAL RELEVANCE

Feline 'lung-digit syndrome' describes an unusual pattern of metastasis that is seen with various types of primary lung tumours, particularly bronchial and bronchioalveolar adenocarcinoma. Tumour metastases are found at atypical sites, notably the distal phalanges of the limbs; the weightbearing digits are most frequently affected, and multiple-digit and multiple-limb involvement is common. Often primary lung tumours in cats are not detected because of clinical signs referable to the primary tumour; rather, many cases present with signs referable to distant metastases. Other sites of metastases from feline primary lung tumours include the skin, eyes, skeletal muscle and bone, as well as multiple thoracic and abdominal organs. These lesions are thought to arise from direct arterial embolisation from the tumour. Indeed tumour embolisation to the aortic trifurcation is possible.

PATIENT GROUP

Primary lung neoplasms are uncommon in the cat. Older animals are most affected (mean age at presentation 12 years, range 2-20 years). There is no apparent sex or breed predilection.

CLINICAL CHALLENGES

Feline lung-digit syndrome presents a diagnostic challenge. Typically there is swelling and reddening of the digit, purulent discharge from the nail bed, and dysplasia or fixed exsheathment of the associated nail. While these signs might be suggestive of infection, this could be secondary to a digital metastatic lesion, particularly in a middle-aged or elderly cat. Radiographic evidence of extensive bony lysis of the distal phalanx, which can be trans-articular to the second phalanx, raises the index of clinical suspicion for metastasis of a primary pulmonary tumour. Thoracic radiography is warranted prior to any surgery or digital amputation as the prognosis is generally grave for cats with this syndrome, with a mean survival time of only 58 days after presentation.

EVIDENCE BASE

This article reviews the previous literature and case reports of feline lung-digit syndrome and feline primary pulmonary neoplasia in general, discussing the course of this disease and the varying clinical presentations associated with different sites of metastasis.