The genesis of embryonic tumors is attributable to primordial germ cells (PGC = primordial germ cells) intended to form gametes (spermatozoa and oocytes). These germinal cells are of epiblastic origin on the one hand and on the other the somatic or nourishing cells which will surround the germinal cells. These somatic cells constitute the somatic gonadal blastema, the exact origin of which remains debated. The most common hypothesis has them coming from at least three sources: the mesonephros, the local mesenchyme, and the coelomic epithelium [13] [14] .

Thus by considering the path of migration of germinal cells from the yolk sac towards the lumbar region (10th dorsal vertebra), passing through the primitive intestine, the mesentery and the existence of undifferentiated gonad, we can easily understand the different Probable locations of germ cell tumors: yolk sac, testicles, ovaries, midline of the body, lumbar region, etc.

Embryonic tumors (ET) are uncommon in the general population, but their incidence remains high in children where they represent the second most common type of cancer in children and adolescents after leukemia. Few studies have been carried out on ET due to their rarity (around 400 cases/year diagnosed in people < 15 years of age in mainland France) [1] . The histological type of childhood cancer is very particular since carcinomas, which represent the vast majority of adult tumors, are practically rare in children. In this case, in addition to leukemias and lymphomas which represent 45% of malignant conditions, we mainly find so-called embryonic tumors and then sarcomas more similar to adult tumors. Most studies address embryonal tumors separately, by system, age group such as in children or simply malignant tumors. A study showed a proportion of 4.7% and sex ratio M/F of 0.9 of embryonal tumors for all tumors of the nervous system of children, while extra-gonadal and extra-cranial germ cell tumors have a proportion of 0.9 and sex ratio M/F 0.2 and 1.1 and 0.2 for gonadal malignant germ cell tumors [15] . Others report a frequency of 1% - 5% of extra gonadal germ cell tumors out of all germ cell tumors [10] . Germ cell tumors represent 20% of ovarian tumors, occupying second place after epithelial tumors [16] . While they represent 3% to 15% of malignant ovarian tumors in East Asian countries [17] . Seminoma is the most common testicular germ cell tumor and often occurs between the ages of 15 and 35 years [18] .

This is a retrospective descriptive study, based on the archives of biopsies (blocks and slides) recorded in the laboratory of the Department of Pathological Anatomy of the University Clinics of Kinshasa. Our study covered a period of 21 years, from January 2000 to December 2021.

Demographic parameters: age; gender;

Clinical parameters: collection site (organ); clinical information.

Pathological parameters: histological nature; histological type; under histological type.

Figures 1-7 illustrate the different pathological entities encountered during our study.

All specimens had been fixed in 10% formalin, dehydrated and cleared, embedded in paraffin, cut with a microtome at 3 - 5 microns and stained with EO. The general architecture of the tissues was observed at low magnification (×4). To highlight tumor cells and clarify their histological type, we used medium and high magnifications (×10 and ×40). The participation of connective fibers was highlighted using trichrome staining. The slides were read again using an OLYMPUS BX41 co-observation microscope. The final results were retained after rereading all the slides by two examiners as independent readers; in the event of discrepancy in the results, a third examiner was used. Table 2 shows the materials used in this study.

The data were entered into an Excel spreadsheet, then exported into R software version 5.26 for processing and statistical analysis. Categorical or qualitative variables were described using frequency tables (simple or crossed). Dependencies or connections between qualitative variables were tested using the Chi-square association test or logistic regression. The central tendency and dispersion parameters were used to summarize the information from the quantitative variables. A nonparametric test was used when the assumptions for using a parametric test did not allow it. All tests were carried out at the 5% significance level, the p-value was preferred to confidence intervals for the significance of statistical differences.

Given its documentary nature, the study respected anonymity and did not require the prior consent of patients, given the usual practice of biopsies, operating specimens from the operating theater, paraffin blocks and archive slides.

In our study, 3168 cases of tumors were diagnosed among which 30 cases were germ cell tumors. N = 3168, n = 30. The frequency of germ cell tumors for our study is 0.94%.

The average age is 22 years with a standard deviation of 17.56 which shows us a strong dispersion around the average whose minimum age is 0 and the maximum is 71 years. The student test (t-test) shows that the p-value is very significant (0.001 < 5%) and the confidence interval for the mean within the study population is between 16 and 29 years. The female gender was the most represented with more than 66.6% of cases. Sex ratio = Number of men/Number of women (Sex ratio = 10/20 = 0.5). The male/female sex ratio was 0.5, which shows a strong female predominance. We note a predominance of benign TG in women at 70% compared to 30% in men. On the other hand, we observe a perfect equality of 50% in both sexes for malignant TG. However, there is a 100% predominance of seminomatous TG subtypes in the male sex.

Table 3 shows a predominance of benign TG in women at 70% compared to 30% in men. On the other hand, we observe a perfect equality of 50% in both sexes for malignant TG. However, there is a 100% predominance of seminomatous TG subtypes in the male sex.

Table 4 shows a predominance of benign TG with 60% of cases, while malignant TG 40% on the one hand and on the other hand, a predominance of non-seminomatous subtype at 83.3%.

Table 5 shows a predominance of benign TG and the non-seminomatous histological subtype in the age group from 0 to 10 years with 56% and 36% respectively.

Table 6 shows a slight predominance of gonadal localization of TG which represents approximately 53% of cases.

Table 7 shows that extragonadal TG is respectively more found in the sacrococcygeal region with 36% of cases.

Our study found a low frequency of TG of 0.94%. The sex ratio is (M/F = 0.5), which shows a predominance of females. Our results differ from those of Kripa Varghese et al. who found a M/F sex ratio of 1.22 [3] and Jankowski et al. 1.2 [15] . This can be explained by the fact that they studied urogenital tumors in children and adolescents for the first and the second all tumors of children and adolescents, while we considered TG in the general population.

The average age at the time of diagnosis was 22 years with a standard deviation of 17.5, which shows a strong dispersion around the average, the minimum age of which is 0 and the maximum is 71 years.

These results are similar to those of Nisrine Mamouni et al. [29] . Who found 22 years as the average age for malignant germ cell tumors, while this age for us is for malignant and benign TG.

They are a little closer to those of Cano Garcia et al., who found an average age of 28 years [30] . On the other hand, our results are different from those found by Bastos et al. and Monagel et al., who found respectively 30 years as the median age (study on testicular TG) [31] and 4.71 as the mean age in his (study on extracranial TG) [32] .

This difference could be explained for the first by the fact that he worked on testicular TG only, while the second studied TG in children aged 0 to 14 years. We also note that TG are not only the prerogative of the gonads, but gonadal locations represented 53% while extragonadal locations only 47%.

We found a male/female sex ratio of 0.5, which shows a strong female predominance. This result is contradictory with AB Effi et al. in Ivory Coast who found a sex ratio of 1.5 (male predominance) [33] . This can be explained by the fact that he worked on a large sample of 556 cases but above all that he worked on all solid tumors in children, leaving aside adults. These results also differ from Hsieh et al. who found a sex ratio of 1.09) [34] . This can be explained by the fact that his study focused on children.

Our study shows a predominance of benign TG overall with 60% and malignant TG with 40%. However, benign TG in females accounted for 70% compared to 30% in males. On the other hand, we observe a perfect equality of 50% in both sexes for malignant TG. However, there is a 100% predominance of seminomatous TG subtypes in the male sex.

These results are different from those found by Kripa Varghese et al. who found 13% of benign teratomas [3] . This can be explained by the fact that they studied urogenital tumors in children under 18 years of age, while we took into account all germ cell tumors in the general population.

The seminomatous subtype represented 13% in our study. These results are different from those found by Bastos et al. who found up to 47.1% of the seminoma subtype in their study on male TG in Brasilia [31] . This can be explained by the fact that they worked exclusively on male patients with a larger sample of 1232 subjects.

We found a predominance of TGs in the gonadal location at 53% and for extragonadal TGs the sacrococcygeal location predominates with 36%, while we did not find any intracranial locations (intracranial TGs 0%). These results are similar to those of Dania A et al. who found a predominance of gonadal TG while in extragonadal locations the sacrococcygeal region was the most found [32] .

These results differ from those of Jankowski M et al. who rather found a pre-dominance of intracranial TG and Hsieh et al. found a predominance of patients with intracranial TG in (53%) of cases [34] . This discrepancy can be explained by the larger sample size of the first (662 patients and a longer period of 31 years, compared to 30 cases in a period of 22 years for our study) but above all because of our limited means and difficult access to brain biopsies [15] .

De Felici M et al. reports frequencies of germ cell tumors ranging from 1% to 5% [10] . While our study shows up to 47% extragonadal localization of germ cell tumors, this clearly illustrates the variability of results on the subject.