850255 research-article2019 JOR0010.1177/2055116919850255Journal of Feline Medicine and Surgery Open ReportsMallol et al Case Series Journal of Feline Medicine and Surgery Open Dystrophic mineralisation in chronic Reports 1­–7 © The Author(s) 2019 exogenous lipid pneumonia in cats Article reuse guidelines: sagepub.com/journals-permissions https://doi.org/10.1177/2055116919850255 DOI: 10.1177/2055116919850255 journals.sagepub.com/home/jfmsopenreports This paper was handled and processed by the European Editorial Office (ISFM) Claudia Mallol1 , Yvonne Espada1,2, Albert Lloret3, for publication in JFMS Open Reports Raúl Altuzarra1 , Carlo Anselmi1 and Rosa Novellas1,2 Abstract Case series summary Exogenous lipid pneumonia with mineralisation of the lung parenchyma was diagnosed in three cats with radiographs, CT and/or bronchoalveolar lavage cytological findings. All three cats had a common clinical history of chronic constipation and long-term forced oral administration of mineral oil. All three cases showed radiographic findings compatible with aspiration pneumonia, with an alveolar pattern in the ventral part of the middle and/or cranial lung lobes. Minor improvement of the radiographic lung pattern in the follow-up studies was seen in two cats, and a miliary ‘sponge-like’ mineralised pattern appeared in the previously affected lung lobes months to years after the diagnosis. In one cat, patchy fat-attenuating areas in the consolidated lung lobes were present on thoracic CT. Cases 1 and 2 showed respiratory signs at the initial presentation, while in case 3 the radiographic findings were incidental and the cat had never exhibited respiratory signs. Relevance and novel information This is the first report to describe dystrophic mineralisation of the lung in exogenous lipid pneumonia and also the first to describe the CT features in cats. Exogenous lipid pneumonia should be included in the differential diagnosis in cases of miliary ‘sponge-like’ mineral opacities in the dependent part of the lung lobes on thoracic radiographs or CT in cats, especially in cases of chronic constipation, previously exposed to mineral oil. Keywords: Exogenous lipid pneumonia; chronic pneumonia; lung mineralisation; constipation; mineral oil Accepted: 11 April 2019 Introduction Case series description Exogenous lipid pneumonia (ELP) results from inhala- Case 1 tion or aspiration of oily material. Only isolated cases of A 4-year-old neutered male domestic shorthair cat was ELP have been reported in cats,1–3 dogs4 and horses.5 referred to our institution for evaluation of chronic con- Chronic forced administration of mineral oil used for stipation and acute respiratory distress following forced treatment of constipation and hair balls is the most com- mon cause of ELP in cats.1–3 Clinical signs are non- 1Servei de diagnòstic per la imatge, Hospital Clínic Veterinari, specific and can vary from absent to severe, depending Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain 2Departament de Medicina i Cirurgia Animals, Facultat de on the amount and quality of the lipid aspirated.1,2,6 Veterinària de la Universitat Autònoma de Barcelona, Bellaterra, Treatment of ELP is largely supportive after cessation of Barcelona, Spain the inciting agent. Prognosis depends on the extension of 3Servei de medicina interna, Hospital Clínic Veterinari, Universitat the lesions and the progression to permanent changes Autònoma de Barcelona, Bellaterra, Barcelona, Spain such as fibrosis.1,2 Corresponding author: We report the clinical and imaging findings in three Claudia Mallol DVM, Carrer de l’Hospital s/n, Veterinary Hospital cats with ELP that received mineral oil as a treatment for Clinic, UAB, 08193 Bellaterra, Barcelona, Spain chronic constipation. Email: claudiamallol@gmail.com Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). 2 Journal of Feline Medicine and Surgery Open Reports  Figure 1 Case 1: right lateral and ventrodorsal views of the thorax at (a,b) initial presentation and (c,d) 15 days later. (a,b) Increased soft tissue opacity of the right middle and left cranial lung lobes is visible at initial presentation, with a lobar sign and air bronchograms indicating an alveolar pattern. (a) Note the ventral distribution of the lung pattern in the right lateral view, commonly seen in aspiration pneumonia. (c,d) The alveolar pattern in the right middle and left cranial lung lobes is still present in the follow-up radiographs, with only mild improvement of the radiographic findings mineral oil administration. The cat had been treated con- marked macrophagic inflammation with a neutrophilic servatively with mineral oil (PO q12h) and a low-residue component. The majority of the macrophages con- diet for a 3 year period. Rectal enemas were occasionally tained multiple round, clear and different-sized vacu- performed in case of an episode of constipation. oles compatible with lipid droplets (Figure 2). Both The cat showed low body condition score (BCS), fungal and bacterial culture yielded no growth. abdominal breathing, tachypnoea (80 breaths per min- Constipation episodes persisted 1 year later and subto- ute) and cyanotic mucous membranes on physical exam- tal colectomy was performed. Thoracic radiographs ination. Thoracic radiographs revealed an alveolar were obtained before surgery and a miliary ‘sponge- pattern in the right middle and left cranial lung lobes, like’ mineralised pattern was visible in the previously with a ventral distribution (Figure 1a,b). affected lung lobes (Figure 3). The alveolar pattern in Aspiration pneumonia was suspected and supportive the right middle lung lobe was still present. The cat treatment based on oxygen, antibiotics, systemic corti- was still alive while writing this case series, 7 years costeroids, bronchodilators and intravenous (IV) fluids after the initial presentation, and no recurrence of the was established. Mineral oil was immediately discontin- respiratory signs had been noted. ued. The patient improved clinically and was discharged with antibiotics, inhaled corticosteroids and bronchodi- Case 2 lators 4 days later. A 4-month-old entire female Persian cat was referred to There was only a mild improvement of the lung our institution for chronic constipation and acute vomit- changes on the follow-up thoracic radiographs 2 weeks ing. The cat had been treated with mineral oil (PO q12h) after the initial onset (Figure 1c,d). Bronchoalveolar and rectal enemas with partial response since the begin- lavage (BAL) under general anaesthesia showed ning of the clinical signs. Physical examination revealed Mallol et al 3 low BCS, crackles in all lung lobes in the lung ausculta- improved after 2 days and was discharged with antibiot- tion and abdominal discomfort on palpation. Thoracic ics, systemic corticosteroids, lactulose and a low-residue radiographs showed diffuse increased soft tissue opacity diet. within the lungs, more marked in the cranioventral Two months later, follow-up thoracic radiographs aspect of the thorax, with an alveolar pattern in the right showed an alveolar pattern (similar to that previously and left cranial and the right middle lung lobes. There described) with granular mineral opacities and ‘sponge- was also a focal alveolar pattern with a perihilar distribu- like’ appearance of the previously affected lung lobes tion in the caudal and accessory lung lobes (Figure 4a,b). (Figure 4c,d). Multiple recurrent episodes of respiratory Severe diffuse colon distension was noted in the abdomi- signs were recorded during a year, which partially nal radiographs. Marked scoliosis of the lumbar spine, responded to systemic corticosteroid and bronchodilator partial fusion of the L5–S1 vertebral bodies and decreased therapy. Owing to the refractory medical management, pelvic diameter were also noted, so secondary obstruc- subtotal colectomy was elected as the treatment for the tive megacolon was suspected. Rectal enema was per- obstipation 1 year later. CT of the thorax was performed formed and supportive treatment based on antibiotics, prior to surgery, showing an alveolar pattern with air systemic corticosteroids, bronchodilators and IV fluids bronchograms in all lung lobes, with a ventral distribu- was established for the suspected aspiration pneumonia. tion in the cranial and middle lobes, and a perihilar dis- Mineral oil was immediately discontinued. The patient tribution in the caudal and accessory lung lobes. Within the consolidated lobes, patchy ill-defined fat-attenuating areas and punctiform mineral-attenuating structures were present (Figure 5). Three years later, neither the res- piratory signs nor the constipation reappeared. Case 3 A 6-year-old neutered male domestic shorthair cat was referred to our institution for acute non-ambulatory tetraparesis secondary to a traumatic event. General physical examination was unremarkable. Postural reac- tions were absent in the right limbs and decreased in the left limbs in the neurological examination. Mild cervical hyperesthesia was noted. Previous to the MRI study and as part of the pre-anaesthetic protocol, thoracic radio- graphs were obtained. Increased soft tissue and granular Figure 2 Cytology of the bronchoalveolar lavage of case 1. mineral opacity were present in the caudal aspect of the Quick Panoptic Stain reveals activated macrophages with right middle lung lobe (Figure 6). Previous aspiration of lipid droplets within the cytoplasm mineral oil was suspected as a result of the radiographic Figure 3 Case 1: (a) ventrodorsal and (b) right lateral views of the thorax 1 year after the initial presentation. A miliary mineralised ‘sponge-like’ pattern is visible, affecting the previously consolidated lung lobes 4 Journal of Feline Medicine and Surgery Open Reports  Figure 4 Case 2: (a,b) ventrodorsal and right lateral views of the thorax at initial presentation and (c,d) 2 months later. (a,b) A diffuse increase in soft tissue opacity of the lungs is visible, causing border effacement of the cardiac silhouette and with the presence of air bronchograms, indicating an alveolar pattern. (b) Note the cranioventral and perihilar distribution of the lung pattern in the right lateral view, where air bronchograms are clearly visible and a lobar sign between both left and right cranial lung lobes is present. (c,d) A miliary mineralised ‘sponge-like’ pattern is visible in the previously affected lung lobes and the diffuse alveolar pattern persists 2 months later. (c,d) Note the compensatory hyperinflation of the aerated caudodorsal lung field Figure 5 CT images of case 2 in (a) a transverse plane displayed in a lung window (window level –500 and window width 1400) and (b) in a soft tissue window (window level 40 and window width 350) at the same level, showing the caudal and accessory lung lobes. (a) There is a ventral distributed alveolar pattern with punctiform mineral-attenuating areas in both caudal and accessory lung lobes. Note the air bronchograms in both caudal lung lobes (black arrows) in the lung window. (b) Patchy ill-defined fat-attenuating areas (white arrows) are visible within the consolidated lung lobes in the soft tissue window Mallol et al 5 Figure 6 Case 3: (a) ventrodorsal and (b) left lateral views of the thorax. There is increased soft tissue opacity and granular mineral opacity in the caudal aspect of the right middle lung lobe (black arrows). A lobar sign is visible between the right middle and right caudal lung lobes in the left lateral view (white arrow) changes and the referring veterinarian was contacted for of the patients in human medicine are asymptomatic on further information. The cat had a previous history of presentation. There is also frequently a discrepancy in chronic diarrhoea, tenesmus and recurrent rectal pro- the severity between the radiological and clinical find- lapse 5 years previously. Among others, long-term treat- ings in people, with extensive imaging findings in ment with mineral oil had been established by the asymptomatic patients.6 Cases 1 and 2 showed extensive referring veterinarian for the intestinal problems. No radiological changes and only the first exhibited severe respiratory signs had ever been reported. The MRI find- respiratory signs on presentation. Similarly to what has ings were compatible with an acute non-compressive previously been reported, cases 1 and 2 showed an nucleus pulposus extrusion lateralised to the right at the absence of or minor improvement in the radiographic level of C2–C3 and a treatment based on IV fluids and lung pattern. This may be explained by the inability of cage confinement was established. The patient was dis- the macrophages to metabolise the lipid material, degen- charged 4 days later with mild improvement but still erating and releasing the oil back into the alveoli.4 showing severe right hemiparesis. Six months later, neu- The diagnosis of ELP is based on a history of exposure rological examination showed mild right-sided proprio- to oil, imaging findings indicating aspiration pneumonia ceptive deficits. No respiratory signs have been reported and the presence of lipid-laden macrophages on BAL 1 year later. analysis. BAL may be normal or show lipid-laden mac- rophages, with or without other inflammatory cells.6 In Discussion case 1, BAL demonstrated lipid droplets within the cyto- Exogenous lipid pneumonia is a particular form of aspi- plasm of the macrophages, confirming the suspected ration pneumonia, resulting from accumulation of oily diagnosis of ELP. All three cases had a common clinical compounds of mineral, vegetable or animal origin history of gastrointestinal disorders and long-term within the alveoli.1,2,4 Mineral oil, such as paraffin oil, forced oral administration of mineral oil. Furthermore, has been widely used as a laxative for constipation in in 2/3 cases, radiographic findings were clearly associ- cats.1 The tasteless and mild nature of the mineral oil ated with administration of the lipid. makes it less irritating to mucosal surfaces without elicit- Radiographic features of ELP in the literature are ing a cough reflex when aspirated.4 It may also inhibit described as non-specific, including a mixed interstitial mucociliary transport, subsequently reaching easily the to alveolar pattern involving mainly the dependent por- bronchial tree and reducing its clearance from the res- tion of both cranial lobes and the right middle lung piratory tract.6 lobe,1,6 occasionally forming masses or nodules.4,7 These characteristics of the mineral oil explain the However, to our knowledge, no mineral opacity within chronic and subclinical behaviour of the disease when the lungs has been described in cases of ELP. All three small amounts of lipids are aspirated, such as in case 3, cats showed a pulmonary pattern and a distribution where the radiographic findings were incidental and the compatible with aspiration pneumonia, with an alveolar cat had never exhibited respiratory signs. More than half pattern in the ventral part of the middle and/or cranial 6 Journal of Feline Medicine and Surgery Open Reports  lung lobes. Perihilar distribution has also been reported,2 parenchymal location of the mineral-attenuating areas, similar to case 2, in which the cranioventral aspect of the unlike the intraluminal bronchial location in cases of thorax was also affected. broncholithiasis. High-resolution CT is the best imaging modality for Idiopathic mineralisation in the lung occurs in pul- the diagnosis of ELP in people.6,8 Multiple different non- monary alveolar microlithiasis, a rare disease character- specific pulmonary patterns have been described for ised by intra-alveolar calcium deposits.19 The deposition ELP on CT in people, but the most characteristic finding occurs in the absence of calcium metabolism disorders, is the presence of fat-attenuating areas in the consoli- usually as an incidental finding.20,21 In contrast to our dated lungs.8 This feature has been described in dogs,3 cases, pulmonary lesions are commonly diffuse with a and was also present in case 2, where the alveolar pat- ‘sandstorm appearance’ and not associated with inflam- tern within the affected lung lobes showed negative mation.20 Other differential diagnoses for mineralised attenuating areas. To our knowledge, no descriptions of lung foci include aspiration of contrast media or pulmo- the CT features have been previously described in cats. nary neoplasia with calcification. The clinical history Chronic consolidation and mineralisation of the lung allows exclusion of the first, because none of the three lobes was the characteristic finding in all three cases cats received any contrast media and, in 2/3 cases, an herein. Pathological mineralisation of the pulmonary alveolar pattern preceded the mineralisation. Although parenchyma is rare, and may occur via a metastatic there is a high incidence of mineralisation in bronchopul- mechanism, in which calcium deposits in normal tis- monary tumours in cats,22 imaging findings usually sues, or via a dystrophic mechanism, occurring in previ- include a solitary mass (frequently cavitated) in the cau- ously damaged, degenerated, necrotic or fibrotic lung dal lungs, pleural effusion and signs of tracheobronchial tissue.9 In ELP, chronic accumulation of lipid in the alve- lymph node enlargement.22,23 Besides, there was only oli triggers a pyogranulomatous or foreign body type mild or no progression of the pulmonary lesions in our inflammatory reaction and fibrosis.7 Therefore, a dys- cases, making the possibility of a tumour unlikely. trophic mechanism may explain the mineralisation in our cases. Conclusions Dystrophic mineralisation of the lungs has been ELP should be included in the differential diagnosis in described in chronic pyogranulomatous pneumonia cases of mineral opacities in the dependent part of the caused by mycobacteria in cats.10–12 Unlike in our cases, lung lobes in cats, especially in cases of chronic constipa- perihilar lymphadenomegaly was the most common tion and previous history of exposure to mineral oil. finding in mycobacterial infections, and radiographic Mineral oil is unsafe owing to the risk of ELP and should changes represent usually a multisystemic disease.11 be avoided in cats. We recommend the use of other treat- However, non-tuberculous mycobacteria (NTM) infec- ment options for the management of constipation. tions may be confined to the thoracic cavity, causing consolidation and mineralisation of the lungs,10 similar Conflict of interest The authors declared no potential to cases 1 and 2. There are various reports in the litera- conflicts of interest with respect to the research, authorship, and/or publication of this article. ture of NTM infections as a complicating factor of ELP in people, dogs and cats.13–15 Lipid-rich environments Funding The authors received no financial support for the seem to be essential in some fast-growing species of research, authorship, and/or publication of this article. NTM, acting as a mechanical protection and contribut- ing to the growth and pathogenicity of the organ- ORCID iD Claudia Mallol https://orcid.org/0000-0001- isms.13,15 In our patients, an underlying mycobacterial 7579-6005 infection was considered unlikely considering the clini- Raúl Altuzarra https://orcid.org/0000-0002-8498-1744 cal presentation and the absence of progression of the pulmonary lesions years later not receiving proper References treatment for mycobacteriosis. 1 De Souza HJM, Dos Santos AE, Reis Ferreira AM, et al. 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