Year : 2009 | Volume
: 52 | Issue : 2 | Page : 271--273
Squamous cell carcinoma arising in a mature cystic teratoma
Vishwanath Gupta, Neelam Sood
Department of Pathology, Deen Dayal Upadhay Hospital, Hari Nagar - 110 064, New Delhi, India
B-3/337 GF Paschim, Vihar - 110 063, New Delhi
Two cases of squamous cell carcinoma (SCC) arising in a mature cystic teratoma (MCT) are being discussed for their rarity and pattern of infiltration of tumor cells in the stroma (alpha mode, beta mode and gamma mode), which is a key factor in deciding the prognosis and patient survival.
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Gupta V, Sood N. Squamous cell carcinoma arising in a mature cystic teratoma.Indian J Pathol Microbiol 2009;52:271-273
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Gupta V, Sood N. Squamous cell carcinoma arising in a mature cystic teratoma. Indian J Pathol Microbiol [serial online] 2009 [cited 2019 Jun 24 ];52:271-273
Available from: http://www.ijpmonline.org/text.asp?2009/52/2/271/48944
The reported incidence of malignant transformation in mature cystic teratoma (MCT) is 1.8% among 8000 cases of MCT.  The most common histological types are squamous cell carcinoma (SCC) followed by adenocarcinoma and melanoma (Peterson's review).  Malignancies of somatic type should be diagnosed in MCT when there is evidence of stromal invasion by malignant appearing epithelieum.  Mode of infiltration of tumor cells in the stroma are classified into three patterns.  In alpha mode, the tumor cells invade the stroma expansively with a well defined border between the tumor and the stroma, while in gamma mode, the tumor cells diffusely invade the stroma without a clear border. Beta mode shows intermediate features between alpha and gamma mode.  In addition to the mode of infiltration, stage, grade, vascular involvement and residual tumor are also important prognostic factors in teratomas with malignant transformation. 
A 30-year-old female presented with abdominal mass and abdominal pain with preoperative ultrasonological diagnosis of dermoid cyst. She underwent exploratory laparotomy with ovarian cystectomy and bilateral tubal ligation. Pap smear cervix was negative for malignancy, CA 125 level was 40µ/ml and CEA level was 10 ng/ml preoperatively (Genix). Cystic mass measuring 12cm in diameter was received. Cut surface showed a unilocular cyst containing sebum and hair and a solid grey white area measuring 2cm in diameter.
Microscopic examination from the cyst wall showed mature squamous epithelium, glial tissue and fat. Sections from solid area showed islands of carcinoma cells having clear to eosinophilic cytoplasm, and vesicular nucleus, mild to moderate pleomorphism. Mitosis was frequent and focal intracellular and extra cellular keratin was present (squamoid differentiation) with dense inflammation and extensive necrosis. Pattern of infiltration was gamma mode [Figure 1], and p53 stain showed positivity of moderate intensity.
A 65-year-old female presented with abdominal mass with preoperative diagnosis of right-sided dermoid cyst by ultrasonography. She underwent exploratory laparotomy with abdominal hysterectomy and bilateral salpingo-oophorectomy. Pap smear cervix was negative, CA 125 level was 50µ/ml and CEA level was 12 ng/ml preoperatively (Genix).
Gross specimen consisted of uterus with cervix and bilateral tubes and ovary. Right ovary was cystic measuring 16cm cut surface showed a unilocular cyst containing pultaceous material and hair with solid and necrotic tissue towards one pole of ovary and prominent fatty tissue nodule in the center of cyst. Sections from solid and necrotic area showed identical features as in previous case, except for the mode of infiltration that was alpha mode [Figure 2], and p53 stain showed positivity of moderate intensity. Transformation zone was seen focally [Figure 3]. Elsewhere the cyst wall was replaced by foreign body giant cell reaction. Section from the fatty tissue nodule showed only fat. Sections from the cervix, endometrium, myometrium, right and left tube and left ovary were unremarkable.
Diagnosis of primary moderately differentiated squamous cell carcinoma arising in a mature cystic teratoma was made. Patients were referred to higher center for further treatment. Both cases had a TNM staging (FIGO) of T1aN0M0 with a final pathologic classification of stage 1A.
Reference Range: By enzyme immunoassays (Genix Technology - Vancouver, Canada),
CA 125 - CEA -
Squamous cell carcinoma arising in MCT is extremely rare and there has been even less discussion on its histomorphological analysis and pre-operative diagnosis. In our institution, 100 cases of MCT have been reported in last 15 years; of these only 2 cases of SCC arising in MCT have been diagnosed (incidence: 2%), which is comparable with the reported incidence. , Average age of SCC arising in MCT had been reported to be 58.2 years as compared to 37.5 years with MCT.  Out of the two cases in our hospital, one was in the older age group. It has also been mentioned that mean size of SCC was 152.3mm compared to 48.2mm in MCT, as was also noted in both these cases.  SCC antigen have been suggested to be of help in differential diagnosis between MCT and SCC arising in MCT,  but has no bearing on the prognosis. However, it could not be done in the two cases studied in our hospital.
The malignant component of this tumor sometimes exists in only part of the lesion causing difficulty in its identification grossly. A tumor arising in MCT may appear grossly as polypoidal mass, mural nodule, or mural plaque as an area of hemorrhage and necrosis;  so every case of MCT should be carefully grossed. The malignant component in these two cases presented as solid nodule, In addition, the tumor in the older patient had necrotic areas.
SCC arising in MCT can be seen microscopically as nests of squamous cells infiltrating the stroma as well as cyst lined by malignant squamous cells. Other histological patterns are papillary, insular, verruciform as well as spindle cell pattern. In high-grade tumors, squamous differentiation is inconspicuous.  Microscopically, the two cases showed islands of malignant squamous cells infiltrating the stroma with intra- and extracellular keratin, frequent mitosis and areas of necrosis. Origin from stratified squamous epithelium was observed in one case, though no respiratory lining epithelium was seen unlike the observation by Hirakawa et al . 
As SCC arising in MCT is quite rare one, must exclude metastasis particularly from cervix.Stromal invasion by malignant appearing epithelium should be used as definite criteria for categorizing MCT with malignant transformation. Mode of infiltration of tumor cell in the stroma was first described by Kikkawa et al. ,  in the year 1997. They studied 32 cases of SCC arising in MCT and noticed that 11 patients with alpha mode remained alive without disease, whereas 12 patients showed beta mode, out of which four of them died within 20 months.  Nine patients showed gamma mode; all of them died within 19 months.  Thus, their analysis showed significant differences among these three groups, suggesting that the mode of infiltration is a good predictor of recurrence and prognosis.  The younger patient in this study had gamma mode of tumor infiltration, whereas the older patient had alpha mode of tumor infiltration. However, there is no correlation between age and infiltration pattern in the two cases studied in our hospital; moreover, this has not been mentioned in the previous studies.  Staging, vascular involvement and mode of infiltration are good predictors of recurrence and prognosis of the disease. Mode of infiltration needs to be incorporated in the reporting as a predictive index for survival.
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