An intrapulmonary teratoma associated with thymic tissueAnintrapulmonary teratoma associated with...

Thorax (1975), 30, 582.

An intrapulmonary teratoma associatedwith thymic tissue

D. W. DAY and S. A. TAYLOR

Departments of Morbid Anatomy and Surgery, King's College Hospital,Denmark Hill, London SE5 8RX

Day, D. W. and Taylor, S. A. (1975). Thorax, 30, 582-587. An intrapulmonary teratomaassociated with thymic tissue. A benign teratoma was removed by segmental resectionfrom the upper lobe of the right lung in a girl aged 19 years. This is the twentieth casereport of a teratoma occurring in the lung substance and is of especial interest becauseof the identification of thymic tissue histologically. The significance of this in relationto the pathogenesis of intrathoracic teratoma is discussed.

Only 19 cases of intrapulmonary teratoma havebeen reported in the world literature. Thymictissue has not been described in them. We wishto report a case in which thymic tissue waspresent.

CASE REPORT

A 19-year-old female clerk was admitted on 21July 1974 after referral from another hospital.She had noticed intermittent pain in the rightchest for two years and for three months a coughwith purulent sputum and right-sided pleuriticpain. There had been no haemoptysis and shehad not lost weight. A chest radiograph twomonths before admission showed a round shadowadjacent to the right hilum and this subsequentlyincreased in size. Other investigations incJudeda haemoglobin of 13.6 g/dl, a normal totat anddifferential white blood cell count and an ESRof 30 mm in one hour (Westergren). A tuber-culin test was positive and because the radio-logical appearances suggested a tuberculousadenitis, antituberculous treatment with rifampi-cin and isoniazid was started, but the hilarshadow continued to enlarge (Fig. 1).On examination after referral she was a fit-

looking girl without signs in the chest. A cultuireof the sputum grew commensal organisms oiily.Tomography localized the lesion to the iightupper lobe. A bronchoscopy showed no abnor-mality and the preoperative diagnosis was of atuberculoma.On 25 July 1974 a right posterolateral thoraco-

tomy was performed and a mass measuring

approximately 5X4X 2 cm was found in theanterior segment of the right upper lobe, partiallyadherent to the mediastinum. During mobilizationit discharged yellow sebaceous material. A stan-dard anterior segmental resection was done andthe chest was closed with drainage. The patientmade an uneventful postoperative recovery.The resected segment of lung measured

1IX5X5 cm, and at one pole under the pleuralsurface was an encapsulated partially cysticmass measuring 6X4X3 cm, from the lining ofwhich a white polypoid structure arose. This ex-tended into the distal part of the segmentalbronchus which was bronchiectatic (Fig. 2). Thecut surface showed tissue around the cystic spaceup to 15 cm thick with a variable yellow andwhite appearance, and sebaceous material waspresent around the stalk of the polyp. Thus thecystic space of the teratoma was in direct con-tinuity with the distal part of the segmentalbronchus. The lung tissue surrounding thebronchiectatic area of the bronchus was yellowand firm.

Histologically the proximal part of the seg-mental bronchus was lined by normal respiratoryepithelium which in the bronchiectatic segmentshowed some squamous metaplasia with areas ofulceration. The surrounding lung tissue showedlipoid pneumonia, and the interstitial tissues andalveoli were packed with foamy multinucleatedgiant cells. When traced distally into the cysticcavity of the teratoma the epithelium was pre-dominantly of keratinizing stratified squamoustype beneath which were hyperplastic sebaceous

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An intrapulmonary teratoma associated with thymic tissue

FIG. 1. A postero-anterior chest radiograph showing a roundedopacity in the right hilar region.

0 2 3 4 5 7 1 9 10cm

FIG. 2. The operative specimen showing the teratoma on the left. Inthe centre is the polypoid structure which has been displaced from thebronchiectatic cavity seen above and to its right.

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FIG. 3. Part of the lining of the cystic cavity of the teratoma showing keratinizingstratified squamous epithelium with underlying hyperplastic sebaceous glands and sweatducts, and to the right the shaft of a hair follicle (Haematoxylin and eosin X50).

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FIG. 4. Pancreatic acinar tissue and adjacent epithelial structures (Haematoxylin andeosin X50).



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FIG. 5. Lobules of thymic tissue present at the periphery of the teratoma (Haematoxylinand eosin X20).

* __wA.W6iw TK = m.; J u"s wFIG. 6. Thymic tissue showing several Hassall's corpuscles, the largest of which containsa focus of calcification (Haematoxylin and eosin X200).



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D. W. Day and S. A. Taylor

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FIG. 7. Strands of attenuated thyinic tissute surrounded by fibrous tissue (Haernatoxylinand eosin X 140).

glands with apocrine and eccrine sweat glands.Occasional hair follicles were also seen (Fig. 3).The polyp was covered by a mixture of squamousand respiratory epithelium with underlying skinappendages and mixed serous and mucous glands.Deep to the surface epithelium of the cyst wallwas pancreatic acinar tissue in which islets ofLangerhans were present together with clusters ofglands and different types of epithelium (Fig. 4).Areas of smooth muscle and fat were also seen.No bone, cartilage or nerve tissue was identified.At the periphery of the teratoma at one point wasa prominent focus of thymic tissue with Hassall'scorpuscles (Figs 5 and 6), and from this areathin reticulated strands of thymic tissue couldbe traced completely around the teratoma(Fig. 7).

DISCUSSION

The rarity of intrapulmonary teratomas contrastswith their relative frequency in the anteriormediastinum which is their third commonest sitein the body. In a review article in 1944 Rusbycollected 245 examples of teratoma of the anteriormediastinum, adding six of his own. Since thenmany more have been described in the literature,

whereas up to the present time only 19 cases ofintrapulmonary teratoma have been reported,although in some the exact site of origin has beendoubtful or histology has been lacking. Trivedi,Mehta, and Nanavaty (1966) reported a case oftheir own and reviewed the literature of theprevious 15 cases, and since then further caseshave been described by Bateson, Hayes, andWoo-Ming (1968), Gautam (1969), and Poundand Willis (1969). Apart from this last case,which occurred in an infant, the age of presenta-tion has varied from 16 to 66 years. The com-monest site in the lung has been the left upperlobe, and of the 16 reports with details of thenature of the tumour, nine have been benign andseven malignant.Our case was similar to that described by

Collier et al. (1959) in that the cystic cavity of theteratoma was in direct communication with thedistal part of the segmental bronchus. Pancreaticacinar tissue, with or without islets of Langerhans,is a usual feature of the anterior mediastinaland intrapulmonary teratomas but is rare interatomas in the gonads and other sites.Thymic tissue in association with intrapul-

monary teratoma has not been described before.

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An intrapulmonary teratoma associated with thymic tissue

However, its association with teratoma of theanterior mediastinum is well recognized.Schlumberger (1946), in a study of 16 cases ofanterior mediastinal teratoma, found thymictissue in the capsule in four instances, and em-phasized that sometimes only parts of theteratoma were available for detailed microscopicalstudy. Since then Inada and Nakano (1958), in ahistological study of 15 cases of mediastinalteratoma, found residual thymic tissue adjacent tothe capsule or in marginal areas mixed withtumour tissue in 11 of 15 cases, and in one ofthem completely surrounding the tumour.From his observations Schlumberger proposed

that the site of development of anterior media-stinal teratoma was in thymic tissue, a vieworiginally put forward by Marchand in 1833. Theorigin of teratoma in the thorax, away from theusual site of the thymus in the anterior media-stinum, could be explained by displacement orearly separation of thymic tissue duringembryogenesis. Pound and Willis (1969), tryingto explain the mode of origin of pulmonaryteratoma, suggest that in the early embryo theprimordial teratomatous focus may lie in such aposition in the potential mediastinum that it iscaught up and carried by the respiratory out-growth from the foregut.

In our case it would seem more likely that theteratoma was arising in thymic tissue and notthat the thymic tissue was one of the componentsof the teratoma, since thymic tissue could betraced completely around the periphery of thetumour. In some places the thymic tissue wasobvious, with demarcation into cortical andmedullary zones, without evidence of involutionand with prominent Hassall's corpuscles. Aroundmost of the tumour, however, and extendingfrom this more obvious thymic tissue, were thinstrands of lymphocytic cells with a reticulated

pattern. It is easy to appreciate how this attenu-ated thymic tissue could disappear or be over-looked in a teratoma which has grown beyond acertain size and resulted in compression atrophy.

We should like to thank Mr. A. M. Macarthur forpermission to publish the details of ithis case, Mr. G.Harwood for invaluable technical and photographichelp, and Mrs. V. Rivers for typing the manuscript.

REFERENCES

Bateson, E. M., Hayes, J. A., and Woo-Ming, M.(1968). Endobronchial teratoma associated withbronchiectasis and bronchiolectasis. Thorax, 23,69.

Collier, F. C., Dowling, E. A., Plott, D., andSchneider, H. (1959). Teratoma of the lung.Archives of Pathology, 68, 138.

Gautam, H. P. (1969). Intrapulmonary imalignantteratoma. American Review of RespiratoryDisease, 100, 863.

Inada, K. and Nakano, A. (1958). Structure andgenesis of the mediastinal teratoma. Archives ofPathology, 66, 183.

Marchand, F. (1833). Ber. d. oberhess. Tesellsch furNatur. u. Heilk, 22, 325.

Pound, A. W. and Willis, R. A. (1969). A malig-nant teratoma of the lung in an infant. Journalof Pathology, 98, 111.

Rusby, N. L. (1944). Dermoid cysts and teratomata ofthe mediastinum. Journal of Thoracic Surgery,13, 169.

Schlumberger, H. G. (1946). Teratoma of the anteriormediastinum in the group of military age--Astudy of sixteen cases, and a review of theoriesof genesis. A rchives of Pathology, 41, 398.

Trivedi, S. A., Mehta, K. N., and Nanavaty, J. M.(1966). Teratoma of the lung: report of a case.British Journal of Diseases of the Chest, 60, 156.

Requests for reprints to: Dr. D. W. Day, Departmentsof Morbid Anatomy and Surgery, King's CollegeHospital, Denmark Hill, London SE5 8RX.

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