Hosseini et al. Diagnostic Pathology 2014, 9:9http://www.diagnosticpathology.org/content/9/1/9
CASE REPORT Open Access
LECutaneous mast cell tumor (Mastocytoma):Cyto- histopathological and haematologicalinvestigationsEhsan Hosseini1, Behnam Pedram2, Ali Mohammad Bahrami1*, Mohammad Hossein Jaberi Moghaddam3,Javad Javanbakht4, Fatemeh Emami Ghomi5, Najme Jaberi Moghaddam6, Mobin Koohestani3
and Radmehr Shafiee7
C
CTED ARTIAbstract
Cutaneous mast cell tumours (MCTs) are the most common skin tumours in dogs. Due to the prevalence of canineMCTs and the variable biologic behavior of this disease, accurate prognostication and a thorough understandingof MCT biology are critical for the treatment of this disease. A cytologic diagnosis of mast cell tumor with evidenceof prior hemorrhage was made, and the masses were surgically removed. Cytological evaluation of fine-needleaspirates from the cutaneous mass from the axillary comprised many well-differentiated, highly granulated mastcells with moderate numbers of eosinophils. Nuclei were varied in size and shape with high nuclear’to’cytoplasmicratio, prominent nucleoli, marked atypical and mitotic figures. Microscopically, mass consisted of sheets of neoplasticround cells that formed nonencapsulated nodules in the dermis and infiltrated into the adjacent dermal collagen,and also there was diffuse subcutis invasion of round to pleomorphic tumor cells. Tumor cells had moderate toabundant cytoplasm, round to ovoid nuclei with scattered chromatin, and mitotic figures. In this tumor, cytoplasmicgranules showed atypical metachromasia. In addition, eosinophils were scattered among the mast cells at theperiphery of the nodules. The presence of eosinophils and the observation, at high magnification, of cells withcytoplasmic metachromatic granules. Invasion of the deep subcutaneous fat or cutaneous muscles were a commonfeature of grade III tumour. Finally, a diagnosis of grade III cutaneous mast cell tumor was made.
Virtual slides: The virtual slide(s) of this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4755249151157024.Keywords: Cytology, Pathology, Dog, Mast cell tumor, Grading
RETRABackgroundMast cell tumors (MCTs) are highly invasive and meta-static and are the most frequent round cell tumors indogs, comprising 16–21% of all cutaneous tumors diag-nosed [1,2], and are the most common skin tumors indogs [3], representing about 7% to 21% of all dog skintumors and 11% to 27% of malignant skin tumors in thisspecies [4]. Canine MCTs have variable biologic behaviors,ranging from solitary benign masses that can be curedwith surgery alone to systemic and potentially fatal meta-static disease [5], and are always considered potentially
* Correspondence: [email protected] of Para Veterinary Medicine, Ilam University, Ilam, IranFull list of author information is available at the end of the article
malignant, but their true metastatic potential is not en-tirely known [6].Round cell tumors consist of discrete cells that are
round to oval rather than fusiform. Included in thisgroup are mast cell tumor, histiocytoma, lymphosarcoma(including reticulum cell sarcoma) and transmissiblevenereal tumor. The differential diagnosis of round celltumors by histologic examination without concomitantcytologic characterization may, in some instances, de-pend more on age of animal, growth rate, location oftumor, number of tumors and lymph node involvementrather than histologic criteria. Mastocytosis is a raregroup of diseases characterized by abnormal prolifera-tion and infiltration of mast cells within the tissues. Theskin is most frequently involved but mast cells also
l Ltd. This is an Open Access article distributed under the terms of the Creativeommons.org/licenses/by/2.0), which permits unrestricted use, distribution, andiginal work is properly cited. The Creative Commons Public Domain Dedicationain/zero/1.0/) applies to the data made available in this article, unless otherwise
Hosseini et al. Diagnostic Pathology 2014, 9:9 Page 2 of 5http://www.diagnosticpathology.org/content/9/1/9
RETRACTE
accumulate in the bone marrow, gastrointestinal tract, lymphnodes, spleen, and liver. Mast cell tumors in association withoncocytes thus should be considered supportive evidence ofan FNA diagnosis of adenolymphoma. Mastocytosis shouldbe considered in the differential diagnosis of urticaria andsolitary mastocytomas may remain active into adoles-cence, raising concern for systemic progression [7-13].MCTs are most often graded histologically by the scheme
described by Patnaik et al. [14]. Tumours of grade I are cir-cumscribed, mainly dermal in location, and consist of well-differentiated mast cells with prominent metachromaticcytoplasmic granules. Poor cellular differentiation, ag-gressive growth pattern, moderate to high mitotic activ-ity, mitotic atypia and sparse to absent cytoplasmicgranulation are the major features of grade III tumours.Grade II MCTs constitute an intermediary form be-tween the two other grades, but they tend to infiltratemore deeply than grade I neoplasms [14,15]. MCTs areroutinely diagnosed by cytology and histopathology.
Case presentationAnimal ethicsThe animal was placed in shade, in standard conditions,water ad libitum, and without restriction of movement ac-cording to the guidelines of Institutional Animal EthicalCommittee of the Tehran University of Animal Science,Iran. Surgery was performed under aseptic conditions andsedation by injection of Xylazine hydrochloride (0.05mg/kg) followed by 2% Lignocaine hydrochloride.
Clinical case reportsIn October 2013, a 5-year-old, 7 kg, female black terrierdog was presented to the clinic at the college of VeterinaryMedicine, university of Tehran, with a growing massaround axillary and mobility problems related to the mass,and euthanasia was applied upon the owner’s request andalso taking into consideration the age of the animal andthe size of the mass. The mass spreading into subcutis isof proximal right front leg, was of 2.8 × 2.5 cm size and185 g weight (Figure 1). The mass was surgically resectedand an impression smear of the tissue was prepared andstained with Giemsa. The rest of the tissue was subjectedto histopathologic evaluation.One formalin-fixed, paraffin wax-embedded section of
each neoplasm was stained with haematoxylin and eosin(HE). Tumour was classified independently by two pa-thologists in order to confirm the diagnosis according tothe WHO criteria [16]. Also tumour was graded accord-ing to the criteria proposed by Patnaik et al. [14] andKiupel et al. [17], as well, moderately or poorly differen-tiated (grades I, II or III, respectively) [14,17]. These cri-teria included the following histomorphological features:extent of tumour (invasiveness), cellular morphology,size of cytoplasmic granules, mitotic activity and stromal
D ARTIC
LE
reaction. Invasiveness was assessed as follows: non-invasive (tumours confined to the superficial dermis andinterfollicular spaces); moderately invasive (tumourswith lower dermal and limited subcutaneous tissue inva-sion); highly invasive (tumours with massive infiltrationof subcutaneous and deep tissue). Mitotic activity wasassessed on toluidine blue-stained sections, five highpower fields (hpfs) being evaluated in each case with a ×40 objective. The data were expressed as mean numberof mitoses per hpf (mitotic index) and tumours wereclassified according to the following grading system: 0(mitotic figures absent); 1 (mitotic index ranging from 0to 2 mitoses/hpf ); 2 (mitotic index > 2/hpf ). Invasivenessand mitotic activity assessment were used to define thehistological grade, and also as individually evaluatedparameters.
Hematological findingsA complete blood work was performed. No changeswere noticed in the erythrogram, however, leukogramchanges included leukocytosis (55,245 leukocytes/μL),neutrophilia (27,644 neutrophils/μL) with mild regenera-tive left shift (4,376 band cells/μL).
Cytological findingsCytological examination indicated mast cells with nu-merous metachromatic stained granules. Nuclei werevaried in size and shape with high nuclear’to’cytoplasmicratio, prominent nucleoli, marked atypical and mitoticfigures. The background was filled with granules fromruptured cells and a moderate eosinophils were alsopresent (Figure 2A and 2B).
Histopathological findingsHistopathologically, MCT tumour cells were less wellcircumscribed by connective tissue and neoplasticcells often exhibited an aggressive behavior, high cel-lularity, cellular pleomorphism, and various morpho-logic patterns.However, in some regions of the tumor tissue shows
neoplastic cells extending into the subcutis. Neoplasticcells had distinct cell borders and widely variable amountsof pale to brightly eosinophilic cytoplasm. Furthermore,tumour had neoplastic cells containing numerous fine eo-sinophilic to basophilic cytoplasmic granules consistentwith mast cell granules and also highly pleomorphictumour cells with a high mitotic index, anisokaryosis andinfiltration of the surrounding dermis and subcutis wereobserved (Figure 2C and 2D).
Pathology grading of cutaneous mast cell tumorIn this case is characterized by one or more of the fol-lowing criteria: at least 3 mitotic figures in 5 hpf, at least2 multinucleated (2 or more nuclei) cells in 5 hpf, at
CTED ARTIC
LE
Figure 1 Cytohistophatology of dermal mass from the axillary of the dog. Representative photomicrographs of mass cell tumuor ofPatnaik grade. (A and B) grade III. High-grade mast cell tumour was characterized by highly pleomorphic tumour cells with a high mitotic index,anisokaryosis and infiltration of the surrounding dermis and subcutis. Haematoxylin and eosin stain. Bar, 50 μm. the smears show n were preparedat the initial presentation and stained with Wrigth-Giemsa solution. Histopathologically, The presence of eosinophils and the observation, at highmagnification, of cells with cytoplasmic metachromatic granules and also, neoplastic cells often exhibited an aggressive behavior, high cellularity,cellular pleomorphism, and various morphologic patterns. Eosinophils are present at the periphery of the mass (Figure 1C and D, H&E, 400x).
Hosseini et al. Diagnostic Pathology 2014, 9:9 Page 3 of 5http://www.diagnosticpathology.org/content/9/1/9
RETRAleast 2 bizarre nuclei (highly atypical with marked indenta-tions, segmentation, and irregular shape) in 5 hpf; karyo-megaly (ie, nuclear diameters of at least 10% of neoplasticmast cells vary by at least 2-fold). The selected field was itthat was most highly mitotically active or had the highestdegree of anisokaryosis.Canine cutaneous MCTs were graded according to the
Patnaik and the Kiupel systems [14,17]. Grade III MCTwas poorly demarcated accumulations of poorly differen-tiated mast cells with severe nuclear pleomorphism. In-vasion of the deep subcutaneous fat or cutaneousmuscles were a common feature of grade III tumour. Fi-nally, a diagnosis of grade III cutaneous mast cell tumorwas made.
DiscussionDogs are at risk for cutaneous MCT, which accounts forup to 21% of all skin tumours [3]. The diagnosis ofMCT by cytology or histopathology is straight forward in
the majority of cases, but forming an accurate prognosis ismore challenging [5]. Prognostic factors of significance in-cluded grading (cytology and histopathology), staging (re-gional and distant metastases), breed, tumour localisationand treatment (surgery, radiation and chemotherapy).Cytological examination after fine needle aspiration isuseful in establishing the diagnosis but histopathology isneeded for grading [18]. Cytology often is helpful in thediagnosis of MCTs because of the characteristic appear-ance of mast cells with routine staining. As is the casewith findings from other species, Wright–Giemsa stainresulted in more intensely stained granules in the neo-plastic mast cells. The mechanism of the differences instaining is unclear. Several subtypes of mast cells havebeen identified in humans and dog based primarily ongranule contents and biological function.This study clearly showed a cellular infiltrate of mast
cells, mononuclear cells and eosinophils in the thick-ened, hyperplastic, and hyperkeratinized epidermis. Mast
Figure 2 Macroscopical examination of a cutaneous cell tumorin a black terrier. The mass spreading into subcutis is of proximalright front leg.
Hosseini et al. Diagnostic Pathology 2014, 9:9 Page 4 of 5http://www.diagnosticpathology.org/content/9/1/9
RETRACTEcells and eosinophils, as opposed to the mononuclearcells of delayed hypersensitivity, predominated, suggest-ing an immediate hypersensitivity reaction. Once acti-vated, mast cells at the edge of a wound are known torelease inflammatory mediators within injured tissue bydegranulation [19]. Thus, it would seem that immediatehypersensitivity reactions may be responsible for thedevelopment of skin lesions due to tumor in dogs. How-ever, the present results suggest that the intense prolifera-tion of mast cells following tumor occurs predominantlyin the skin.The results of this study suggest that cellular prolifera-
tion plays a significant role in the progression of canineMCTs. Although the results of this study confirm the re-sults of previous studies that have shown the prognosticsignificance of cellular proliferation in canine MCTs[14,15,18,19] cellular proliferation should not be evalu-ated as a single prognostic factor for canine MCTs butshould be evaluated in tandem with additional prognos-tic indicators. Furthermore, the histologic characteristicsof the MCT cells in this affected dog was moderate toabundant cytoplasm, round nuclei with scattered chro-matin, fibrous stroma, and eosinophil infiltration. Littlenecrosis was seen.Several grading systems have been proposed to classify
canine mast cell tumors. The system most commonlyused classifies the tumor from grades I to III, dependingon how well the mast cells are differentiated, mitotic ac-tivity, location within the skin, invasiveness, and thepresence of inflammation or necrosis, with grade III be-ing the most aggressive (characterized by the presence ofundifferentiated, immature mast cells with a high poten-tial for metastasis) [20,21]. In the current case, the
D ARTIC
LE
presence of multiple large nodules, the extension intothe dermis, and the poorly differentiated mast cellscould be comparable to grade III described for dogs. Re-cently, a new 2-tier histologic classification for caninecutaneous tumors has been proposed [22]. This gradingsystem is based on the presence of mitotic figures, mul-tinucleated cells, bizarre nuclei, and karyomegaly to pre-dict biological behavior, likely time to metastasis, newtumor development, and survival time. In the presentcase, although the neoplasia did not show any of thesehistological parameters, the presence of multiple cutane-ous tumors suggests a malignant behavior. Grade III tu-mours have a very poor prognosis even with treatment,which might discourage owners from extensive surgery.This may explain the discrepancy in surgery performedin MCT cases of different grades. This result agrees withthe findings by Murphy et al. [23] that showed dogs withpoorly differentiated tumours had a significantly shortersurvival time. These results suggest that all multiple cu-taneous MCTs should be treated as individual neoplasmsand prognosis should be dependent on individual vari-ables such as grade and not related to the number of tu-mours present, which was shown not to affect survival.Mitotic index and size were not found to be independentpredictors of survival.
ConclusionsIn conclusion, this study described cytohistopathology fea-tures of canine cutaneous MCTs of the skin region. Thehistological features of these tumours would suggest thatmost should be classified as high-grade MCTs. A cutane-ous MCT may be diagnosed on the basis of observing thehistopathological pattern described in present study.Moreover, the use of grading system for a tumor type maybe helpful in distinguishing this type of neoplasm fromother malignancies with similar morphology. Further-more, this study demonstrated that in canine cutaneousMCTs, may be used as a sensitive prognostic indicator ofpost-surgical tumour behaviour; in addition, it is related toother histopathological variables that are widely acceptedas having prognostic value.
Competing interestsThe authors declare that they have no competing interests.
Authors’ contributionsEH, BP and AMB participated in the histopathological evaluation, performedthe literature review, acquired photomicrographs and drafted the manuscriptand gave the final histopathological diagnosis. MHJM, FEGH, JJ, NJM, MK andRSH designed and carried out all the experiments and the principalinvestigators of the laboratory in which the research were performed andcontributed to the interpretation of the data and writing of the manuscript.All authors read and approved the final manuscript.
AcknowledgementsThe authors thank staff of the Department of pathology, Faculty ofVeterinary Medicine, Tehran University for their valuable technical assistance.
D ARTI
Hosseini et al. Diagnostic Pathology 2014, 9:9 Page 5 of 5http://www.diagnosticpathology.org/content/9/1/9
RETRACTE
Author details1Faculty of Para Veterinary Medicine, Ilam University, Ilam, Iran. 2Departmentof Pathobiology, Susangerd Branch, Islamic Azad University, Susangerd, Iran.3Graduate, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.4Department of Pathobiology, Faculty of Veterinary Medicine, TehranUniversity, Tehran, Iran. 5Graduate, Faculty of Medicine, Iran University ofMedical Sciences, Tehran, Iran. 6MSc, Clinical Biochemistry, Tarbiat ModaresUniversity, Tehran, Iran. 7Graduate, Faculty of Veterinary Medicine, TehranUniversity, Tehran, Iran.
Received: 11 December 2013 Accepted: 5 January 2014Published: 20 January 2014
References1. Misdorp W: Mast cell and canine mast cell tumors: a review. Vet Q 2004,
26:156–169.2. Brodey RS: Canine and feline neoplasia. Adv in Vet Sci Comp Med 1970,
5. Welle MM, Rohrer Bley C, Howard J, R€ufenacht S: Canine mast celltumours: a review of the pathogenesis, clinical features, pathology andtreatment. Vet Dermatol 2008, 19:321–339.
6. Webster J, Yuzbasiyan-Gurkan V, Miller R, Kaneene J, Kiupel M: Cellular pro-liferation in canine cutaneous mast cell tumors: associations with c-KITand its role in prognostication. Vet Pathol 2007, 44:298–308.
7. Maki K, Chihoko H, Yukiko M, Fumi K, Shigeo H, Hiroshi M, Tomoo I: Primarysubmucosal nodular plasmacytoma of the stomach: a poorly recognizedvariant of gastric lymphoma. Diagn Pathol 2013, 8:30.
8. Rong-Jun M, Zhi-Ming J, Hui-Zhen Z, Xiong-Zeng Z, Qing-Ling Z: Clinicaland pathological characteristics of giant cell angioblastoma: a casereport. Diagn Pathol 2012, 7:113.
9. Armah HB, Anil V: Malignant perivascular epithelioid cell tumor (PEComa)of the uterus with late renal and pulmonary metastases: a case reportwith review of the literature: Parwani. Diagn Pathol 2007, 2:45.
10. Shafiee R, Javanbakht J, Atyabi N, Bahrami A, Kheradmand D, Safaei R,Khadivar F, Hosseini E: Comparative value of clinical, cytological, andhistopathological features in feline mammary gland tumors; anexperimental model for the study of human breast cancer. Diagn Pathol2013, 8:136.
11. Shafiee R, Javanbakht J, Atyabi N, Kheradmand P, Kheradmand D, Bahrami A,Daraei H, Khadivar F: Diagnosis, classification and grading of caninemammary tumours as a model to study human breast cancer: an Clinico-Cytohistopathological study with environmental factors influencing publichealth and medicine. Cancer Cell Int 2013, 13(1):79.
12. Khaki F, Javanbakht J, Sasani F, Gharagozlou MJ, Bahrami A, Moslemzadeh H,Sheikhzadeh R: Cervical type AB thymoma (Mixed) tumour diagnosis in amynah as a model to study human: clinicohistological,immunohistochemical and cytohistopathological study. Diagn Pathol 2013,8(1):98.
13. Tavasoly A, Javanbakht J, Khaki F, Hosseini E, Bahrami A, Hassan MA,Mirabad M: Ulnar malignant peripheral nerve sheath tumour diagnosis ina mixed-breed dog as a model to study human: histologic, immunohis-tochemical, and clinicopathologic study. Diagn Pathol 2013, 8(1):86.
14. Patnaik AK, Ehler WY, MacEwen EG: Canine cutaneous mast cell tumors:morphologic grading and survival time in 83 dogs. Vet Pathol 1984,21:469–474.
15. Gross TL, Ihrke PJ, Walder EJ, Affolter VR: Epithelial Neoplasms and OtherTumors. 2nd edition. Blackwell Publishing: Skin Diseases of the Dog and Cat:Clinical and Histopathologic Diagnosis; 2005:641–654. Section 2, Part I.
16. Goldschmidt MH, Hendrick MJ: Tumors of the skin and soft tissues.. InTumors in Domestic Animals. 4th edition. Edited by Meuten DJ. Ames, Iowa:Iowa State Press; Blackwell. Publishing Company; 2002:64–67.
17. Kiupel M, Webster JD, Bailey KL, Best S, Delay J, Detrisac CJ, Fitzgerald SD:Proposal of a 2-tier histologic grading system for canine cutaneous mastcell tumors to more accurately predict biological behavior. Vet Pathol2011, 48:147–155.
CLE
18. Bronden LB, Eriksen T, Kristensen AT: Mast cell tumours and other skinneoplasia in Danish dogs–data from the danish veterinary cancerregistry. Acta Vet Scand 2010, 22:52–56.
19. Noli C, Miolo A: The mast cell in wound healing. Vet Dermatol 2001,12:303–313.
20. Bostock DE: Neoplasms of the skin and subcutaneous tissues in dogs andcats. Br Vet J 1986, 142:1–19.
21. Weisse C, Shofer FS, Sorenmo K: Reoccurrence rates and sites for grade IIcanine cutaneous mast cell tumors following complete surgical excision.J Am Anim Hosp Assoc 2002, 38:71–73.
22. Simoes JP, Schoning P, Butine M: Prognosis of canine mast cell tumors: acomparison of three methods. Vet Pathol 1994, 31:637–647.
23. Murphy S, Sparkes AH, Blunden AS, Brearley MJ, Smith KC: Effects of stageand number of tumours on prognosis of dogs with cutaneous mast celltumours. Vet Rec 2006, 158(9):287–291.
doi:10.1186/1746-1596-9-9Cite this article as: Hosseini et al.: Cutaneous mast cell tumor(Mastocytoma): Cyto- histopathological and haematologicalinvestigations. Diagnostic Pathology 2014 9:9.
Submit your next manuscript to BioMed Centraland take full advantage of:
• Convenient online submission
• Thorough peer review
• No space constraints or color figure charges
• Immediate publication on acceptance
• Inclusion in PubMed, CAS, Scopus and Google Scholar
• Research which is freely available for redistribution
Submit your manuscript at www.biomedcentral.com/submit
