Case Report 90
Primary Mucoepidermoid Carcinoma of the ThymusA Rare Cause ofMediastinal Thmour I. Brightman. 1. A. Morgan . W P. Kunz e. and M. N. Sheppa rd" l ungenklinik Herner. Herner/Germany • Department oflun g Pathology. RoyalBrompton NationalHeart & lun g Hospital. lo ndon. England
We present a primary mucoepidermoid carcinoma of the thymus which is an extremely rare cause of mediastinal tumour. Growth is slow with cure obta ined after complete resection. Only two previous cases have been reported. Keywords Mucoepidermoid carcinoma - Mediasti num - Thymus
Case Report A 70-year -old fem ale was a dmitted to Lungenklinik Hern er in Ju ne 1990 co m plaining of retrosternal pain and dyspn oea on exe rtion for ove r 1 year. Ther e was no h istory of m ya sthenia gr avis. Th e ph ysical exam in ation was unrem arkab le . A che st radiograph s howed a retrosternal tumour. Th is findin g wa s con firm ed by computer ised tomography and was co m p atible with an invasive lesion (Fig . 1). Oth er preop erative investi gati on s were n ormal and m etas tases else w he re ha d b een exclude d.
Prlmares mukoepidermoides Karzinom des Thymus : Eine se lte ne Ursac he eines mediastinalen Tumors Wir berichten tiber eine 70jiihr ige Patientin. die mit retroster nalen Schmerzen und einer Belastungsdyspnoe zur Aufnahme gelangte. Bei der Untersuchung zeigte sich ein retrostern al wachsender Tumor mit Zeichen der lnvasivitat ohne Anhalt fur Metastasen, Ober eine mediane Stern otomie wurde der Tumor. der das Perikard und beide Pleuren infiltriert hatte, in toto entfernt. Bei der histologischen Aufarb eitung handelt es sich urn ein langsam wachsendes mucoepidermoides Karzin om. Der vorliegende Fall wird anhand der Literatur diskutiert.
A media n st ernotomy was performed and an inva sive tumour foun d . It had infiltra ted th e su pe rficial layer of the pericardium an d both th e rig ht and left pleurae. Th e tumour was removed in total with partial resection of th e pericardium a nd both pleura e and was conside re d to be macroscopica lly co m pletely resected . Th e postop erative cou rse was entirely un even tful and th e patien t was disch a rged fit an d we ll. as she was at follow-up 1 year later .
Path ology Th e tumo ur was round and firm with attache d pericardium an d pleu ra. it m eas ured 11 x 5 x 4. 5 em . On cutt ing it had a lobulated a ppearance with n o evidence of haem orrhage or n ecr osis . Light mi croscop y revealed th at the tumour ce lls were e pithe lial a n d arra nge d in nests sepa rated by den se fibrou s tissu e . Th e cells consiste d of a mi xture of ce lls. Ma ny we re polygon al with pink cytoplasm a nd round to oval nu clei in keeping with squamous cells . Th es e ce lls s howed transition to a second ce ll typ e which was larger with int racyto plas mic vac uol es filled with m ucin (Fig . 2 a ). These cells were predomin ant in the tumour n ests . Th ere were few mi toses an d no evide nc e of n ecrosis . Th e appearance was that of a m ucoe pidermo id ca rcin om a of low gr ade . Normal thym us surro un ded th e tumou r (Fig . 2 b). Pleura and peri cardi um we re infiltrated by tumour but resect ion margins were free . Dis cussion
Fig. 1 CAT Scan of mediastinum showinganterior mediastinaltumour
Thorac. cardiovasc. Surgeon 40 (1992) 90-9 1 © Georg Thieme Ve rlagStuttgart · New Yo rk
Only 94 cases of thy mic ca rci noma have been rep orted up an d un til 1990 (1) . In contras t to thy momas th ey s how
Re cei ved for Publication: October 2, 1991
Downloaded by: University of British Columbia. Copyrighted material.
Summa ry
Thom c. card iov asc. Surgeon 40 (1992)
Fig.2 Nest oftumourcellsshowi ngsquamouscellsonthe left merging into larger paler cells onthe rightwhichare vacuolatedandfilled with mucin. Transitional cells liebetween. Haematoxylinand eosin x 400
Fig. 2 b Tumournest onthe right infiltrates thymus onthe leftsidewith Hassal's corpuscle (') x 400
cytological evide nce of malignancy and usu ally are high grade and aggr essi ve tumours . Th e m ost com mo n histologica l types a re lymphoepithelioid-like ca rc ino m as, squamous carcin om a s, small-ce ll, clear-cell, ad en osquamous , basal oid , sa rcom a toid, and undifferentiated ca rcinomas (7). Mucoepidermoid ca rci nom a of thymus is extre me ly rare and was first described in 1982 (3, 5) with on ly tw o cases bein g documented . This tumour is cytologica lly similar to low gr ad e mucoepidermoid tumour of saliva ry glands (6). Th e case rep orted by Sno oen et al. (3) was complete ly encaps ula te d, resected a nd had no evide nce of recurren ce 2 years la ter, while th e othe r case (5) was infiltrating th e peri cardium an d co uld not be removed com plete ly. Th e pati ent died of ca r diac tamponade 3 years aft er surge ry . It thus a ppears that mu coepidermoid carcinom a of th e th ymus is extr eme ly rare a nd ca n be cure d with com plete res ection. Ade nosqua m ous ca r cinom a s of th e th ymus in which squamou s a re a s mingle with glandular areas do not have th e nesting or tr ansitiona l cell areas seen in mucoepidermoid carcinomas. It is interesting to note th at th e more gla nd ula r differentiation in th ymi c carcinomas th e bett er th e prognosis (2). A recent report on 60 thymic carcinom as divid ed th em into high gra de tumours with 84 % dying of the diseas e (lympho epitheliom a, clear -cell, ad enosquamous , small-cell, sarc omatoid a nd undifferentiated) and low gr a de w ith none dyin g of dis ea se (we ll-differe ntiate d squamous cell car cinoma, mu coepidermoid, and basaloid ca rcinoma) (4). Th e on e mu coepidermoid ca r cinom a in this seri es was previou sly r eported (3). We here pres ent onl y th e third reported case of a mu coepidernoid carcinoma of the th ymus which should be cons ide re d a mo ng th e differential'diagn os es of a m ediastinal mass. It is a low grade tumour a nd com plete r es ection should be a ime d for.
Ack nowle dgement We wish to th ank Dr. Moormann, Institut e of Radio logy, Kaiserstr. 68 , 46 00 Dortmu nd/ Germany who kind ly provided th e CAT Scan .
Re fer ence s I
Hartma nn , C. A.. Chr. Roth. C. Minck. and G. Niedobitek: Thymic
2
Ma tsu no, Y.. K. Mukai. M. Noguchi. Y. Sa to , and Y. Shimosato:
carcinoma. J. Cancer Res. Clin. Oncol. 116 (1990) 69-82 Histochemical and Immunohistochemical Evidence of Glandul ar Diffe rentiation in Thymic Carcinoma. Acta Pathol. Jpn . 39 (1989) 433-438 3 S nov er. D. Coo G. D. Levine. and J. Rosai : Thymic Carcinoma. Am. J. Surg. Pathol. 6 (1982) 451-470 • Suster, S: and J. Rosai.· Thymic Carcinoma. A Clinicopathologic Study of 60 cases. Cancer 67 (1991) 1025-1032 Tanaka. Moo R. Shimoktuoa, O. Mats ubara. N. Ao ki. R. Kamiyama. T. Kasu ga. and S. Hatak ey am a: Mucoepidermoid carcinoma of the thymic region. Acta Pathol. Jpn . 32 (1982) 703-712 6 Thackr au, A. c.. and R. B. Lucas: Tumours of major salivary glands . In:Atlas ofTumour Pathology(2nd ser ies. fasc. lO)A.F.I.P. Washing ton DC 1974 7 Truong, L. o.. D. R. Mody. P. 7: Cagle. G. L. Ja ckson-York. M. R. S chwa rtz. and T. M. Whee ler: Thymic Carcinoma. Am. J. Surg. Pathol. 14 (1990) 151-1 66
Dr. M. N. S heppard
Department of Lung Pathology Royal Brompton National Heart & Lung Hospital Sydney Street GB-London SW3 6NP Great Britain
91
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Primary M ucoepid ermo id Ca rci no ma of th e Thy mus -A Rare Ca use of M ediastinal Tum our
Primary Mucoepidermoid Carcinoma of the ThymusA Rare Cause ofMediastinal Thmour I. Brightman. 1. A. Morgan . W P. Kunz e. and M. N. Sheppa rd" l ungenklinik Herner. Herner/Germany • Department oflun g Pathology. RoyalBrompton NationalHeart & lun g Hospital. lo ndon. England
We present a primary mucoepidermoid carcinoma of the thymus which is an extremely rare cause of mediastinal tumour. Growth is slow with cure obta ined after complete resection. Only two previous cases have been reported. Keywords Mucoepidermoid carcinoma - Mediasti num - Thymus
Case Report A 70-year -old fem ale was a dmitted to Lungenklinik Hern er in Ju ne 1990 co m plaining of retrosternal pain and dyspn oea on exe rtion for ove r 1 year. Ther e was no h istory of m ya sthenia gr avis. Th e ph ysical exam in ation was unrem arkab le . A che st radiograph s howed a retrosternal tumour. Th is findin g wa s con firm ed by computer ised tomography and was co m p atible with an invasive lesion (Fig . 1). Oth er preop erative investi gati on s were n ormal and m etas tases else w he re ha d b een exclude d.
Prlmares mukoepidermoides Karzinom des Thymus : Eine se lte ne Ursac he eines mediastinalen Tumors Wir berichten tiber eine 70jiihr ige Patientin. die mit retroster nalen Schmerzen und einer Belastungsdyspnoe zur Aufnahme gelangte. Bei der Untersuchung zeigte sich ein retrostern al wachsender Tumor mit Zeichen der lnvasivitat ohne Anhalt fur Metastasen, Ober eine mediane Stern otomie wurde der Tumor. der das Perikard und beide Pleuren infiltriert hatte, in toto entfernt. Bei der histologischen Aufarb eitung handelt es sich urn ein langsam wachsendes mucoepidermoides Karzin om. Der vorliegende Fall wird anhand der Literatur diskutiert.
A media n st ernotomy was performed and an inva sive tumour foun d . It had infiltra ted th e su pe rficial layer of the pericardium an d both th e rig ht and left pleurae. Th e tumour was removed in total with partial resection of th e pericardium a nd both pleura e and was conside re d to be macroscopica lly co m pletely resected . Th e postop erative cou rse was entirely un even tful and th e patien t was disch a rged fit an d we ll. as she was at follow-up 1 year later .
Path ology Th e tumo ur was round and firm with attache d pericardium an d pleu ra. it m eas ured 11 x 5 x 4. 5 em . On cutt ing it had a lobulated a ppearance with n o evidence of haem orrhage or n ecr osis . Light mi croscop y revealed th at the tumour ce lls were e pithe lial a n d arra nge d in nests sepa rated by den se fibrou s tissu e . Th e cells consiste d of a mi xture of ce lls. Ma ny we re polygon al with pink cytoplasm a nd round to oval nu clei in keeping with squamous cells . Th es e ce lls s howed transition to a second ce ll typ e which was larger with int racyto plas mic vac uol es filled with m ucin (Fig . 2 a ). These cells were predomin ant in the tumour n ests . Th ere were few mi toses an d no evide nc e of n ecrosis . Th e appearance was that of a m ucoe pidermo id ca rcin om a of low gr ade . Normal thym us surro un ded th e tumou r (Fig . 2 b). Pleura and peri cardi um we re infiltrated by tumour but resect ion margins were free . Dis cussion
Fig. 1 CAT Scan of mediastinum showinganterior mediastinaltumour
Thorac. cardiovasc. Surgeon 40 (1992) 90-9 1 © Georg Thieme Ve rlagStuttgart · New Yo rk
Only 94 cases of thy mic ca rci noma have been rep orted up an d un til 1990 (1) . In contras t to thy momas th ey s how
Re cei ved for Publication: October 2, 1991
Downloaded by: University of British Columbia. Copyrighted material.
Summa ry
Thom c. card iov asc. Surgeon 40 (1992)
Fig.2 Nest oftumourcellsshowi ngsquamouscellsonthe left merging into larger paler cells onthe rightwhichare vacuolatedandfilled with mucin. Transitional cells liebetween. Haematoxylinand eosin x 400
Fig. 2 b Tumournest onthe right infiltrates thymus onthe leftsidewith Hassal's corpuscle (') x 400
cytological evide nce of malignancy and usu ally are high grade and aggr essi ve tumours . Th e m ost com mo n histologica l types a re lymphoepithelioid-like ca rc ino m as, squamous carcin om a s, small-ce ll, clear-cell, ad en osquamous , basal oid , sa rcom a toid, and undifferentiated ca rcinomas (7). Mucoepidermoid ca rci nom a of thymus is extre me ly rare and was first described in 1982 (3, 5) with on ly tw o cases bein g documented . This tumour is cytologica lly similar to low gr ad e mucoepidermoid tumour of saliva ry glands (6). Th e case rep orted by Sno oen et al. (3) was complete ly encaps ula te d, resected a nd had no evide nce of recurren ce 2 years la ter, while th e othe r case (5) was infiltrating th e peri cardium an d co uld not be removed com plete ly. Th e pati ent died of ca r diac tamponade 3 years aft er surge ry . It thus a ppears that mu coepidermoid carcinom a of th e th ymus is extr eme ly rare a nd ca n be cure d with com plete res ection. Ade nosqua m ous ca r cinom a s of th e th ymus in which squamou s a re a s mingle with glandular areas do not have th e nesting or tr ansitiona l cell areas seen in mucoepidermoid carcinomas. It is interesting to note th at th e more gla nd ula r differentiation in th ymi c carcinomas th e bett er th e prognosis (2). A recent report on 60 thymic carcinom as divid ed th em into high gra de tumours with 84 % dying of the diseas e (lympho epitheliom a, clear -cell, ad enosquamous , small-cell, sarc omatoid a nd undifferentiated) and low gr a de w ith none dyin g of dis ea se (we ll-differe ntiate d squamous cell car cinoma, mu coepidermoid, and basaloid ca rcinoma) (4). Th e on e mu coepidermoid ca r cinom a in this seri es was previou sly r eported (3). We here pres ent onl y th e third reported case of a mu coepidernoid carcinoma of the th ymus which should be cons ide re d a mo ng th e differential'diagn os es of a m ediastinal mass. It is a low grade tumour a nd com plete r es ection should be a ime d for.
Ack nowle dgement We wish to th ank Dr. Moormann, Institut e of Radio logy, Kaiserstr. 68 , 46 00 Dortmu nd/ Germany who kind ly provided th e CAT Scan .
Re fer ence s I
Hartma nn , C. A.. Chr. Roth. C. Minck. and G. Niedobitek: Thymic
2
Ma tsu no, Y.. K. Mukai. M. Noguchi. Y. Sa to , and Y. Shimosato:
carcinoma. J. Cancer Res. Clin. Oncol. 116 (1990) 69-82 Histochemical and Immunohistochemical Evidence of Glandul ar Diffe rentiation in Thymic Carcinoma. Acta Pathol. Jpn . 39 (1989) 433-438 3 S nov er. D. Coo G. D. Levine. and J. Rosai : Thymic Carcinoma. Am. J. Surg. Pathol. 6 (1982) 451-470 • Suster, S: and J. Rosai.· Thymic Carcinoma. A Clinicopathologic Study of 60 cases. Cancer 67 (1991) 1025-1032 Tanaka. Moo R. Shimoktuoa, O. Mats ubara. N. Ao ki. R. Kamiyama. T. Kasu ga. and S. Hatak ey am a: Mucoepidermoid carcinoma of the thymic region. Acta Pathol. Jpn . 32 (1982) 703-712 6 Thackr au, A. c.. and R. B. Lucas: Tumours of major salivary glands . In:Atlas ofTumour Pathology(2nd ser ies. fasc. lO)A.F.I.P. Washing ton DC 1974 7 Truong, L. o.. D. R. Mody. P. 7: Cagle. G. L. Ja ckson-York. M. R. S chwa rtz. and T. M. Whee ler: Thymic Carcinoma. Am. J. Surg. Pathol. 14 (1990) 151-1 66
Dr. M. N. S heppard
Department of Lung Pathology Royal Brompton National Heart & Lung Hospital Sydney Street GB-London SW3 6NP Great Britain
91
Downloaded by: University of British Columbia. Copyrighted material.
Primary M ucoepid ermo id Ca rci no ma of th e Thy mus -A Rare Ca use of M ediastinal Tum our
