Introduction

Ovarian cancer encompasses a wide variety of tumors, all with different clinical patterns, histologies, and molecular features. Ovarian cancer is typically classified as epithelial (serous, mucinous, endometrioid, clear cell, carcinosarcoma, and mixed) vs nonepithelial (germ cell and sex cord stromal cell). Epithelial ovarian cancers, which comprise 90% to 95% of all ovarian cancer cases, are more common than nonepithelial ovarian cancer. However, there are a group of ultrarare subtypes such as transitional cell carcinoma, endometrioid carcinoma, neuroendocrine tumors (NETs), mesothelioma, squamous cell carcinoma, and ovarian sarcomas. Most of the literature for these subtypes comes from case reports, small case series, and population database resources whose data sources lack the details necessary to make any specific treatment recommendations. In this chapter, we will review these ultrarare subtypes of ovarian malignancies and make recommendations for treatment based on the current literature as well as drawing from similar histologic subtypes from other primary tumor sites.

Transitional cell carcinoma

Transitional cell carcinoma of the ovary is a rare histological type of epithelial ovarian cancer that was first described in 1987 by Austin and Norris ( Table 8.1 ). Similar to other transitional cell tumors such as Brenner tumors of the ovary, transitional cell carcinomas of the ovary contain urothelial-like tissue that closely resembles transitional cell carcinoma of the bladder. Unlike Brenner tumors, however, they lack the dense stromal calcifications and epithelial-type histologic patterns. In fact, molecular and immunohistochemical studies have further distinguished transitional cell carcinoma of the ovary from Brenner tumors by showing a resemblance to high-grade serous carcinomas. Molecular and genetic analysis also demonstrated that ovarian transitional cell carcinomas follow a tumorigenic pathway like that of high-grade serous tumors with frequent TP53 mutations. In the light of new evidence, in the new WHO classification system released in 2014, transitional cell carcinoma of the ovary is no longer considered a separate entity but a variant of high-grade serous (or rarely endometrioid) ovarian carcinoma.

Very few studies have examined the clinical significance of ovarian transitional cell carcinomas. Given the rarity of this tumor, the true incidence of the disease is unknown, but studies have reported incidences ranging from 1% to 2% of cases of ovarian cancer. The clinical presentation is like that of other epithelial ovarian cancers, including symptoms such as abdominal pain, bloating, back pain, and urinary or bowel symptoms. Given the close resemblance to transitional cell carcinomas of the bladder, the differential diagnosis includes metastatic urothelial carcinoma of the urinary tract. Often, it is very difficult to discern the origin of transitional cell carcinomas based on conventional histological stains alone. While Brenner tumors of the ovary and transitional cell carcinomas of urothelial origin express certain cytokeratins and uroplakins, ovarian transitional cell carcinomas usually do not. Therefore, in some cases, immunohistochemistry may be helpful in distinguishing transitional cell carcinomas of ovarian origin from those of urothelial origin. The lack of expression of urothelial markers also supports the idea that transitional cell carcinomas of the ovary originate from Mullerian epithelium rather than being a urothelial neoplasm.

The gross appearance of the tumor is similar to high-grade serous carcinoma, with no specific distinguishing features. Tumors are large and can be solid and cystic with areas of hemorrhage and necrosis.

As mentioned earlier, the 2014 WHO Classification of Female Genital Tumors transitional cell carcinoma was considered a variant of high-grade serous carcinoma. The 2020 WHO Classification of Female Genital Tumors further highlights that high grade serous carcinoma with homologous recombination-deficiency frequently display solid, endometrial-like and transitional patterns. Tumors with transitional pattern are characterized by large papillae lined by multilayered/stratified epithelium, resembling urothelial mucosa ( Fig. 8.1 ). Microcysts or punched out spaces are typically seen with the epithelium ( Fig. 8.2 ). The nuclei are high-grade with significant pleomorphism. Most cases, upon adequate sampling, show areas of more typical high-grade serous carcinoma with papillary, cribriform, slit-like, and glandular patterns. Transitional cell carcinoma and high-grade serous carcinoma share similar immunophenotype. Both tumors are positive for PAX-8, WT-1 ( Fig. 8.3 ), and hormone receptors.

Tumor with large edematous papillae resembling urothelial mucosa ( black arrow ). Areas of more typical high-grade serous carcinoma with micropapillae ( red arrows ).

High power images showing multilayered epithelium with punched out spaces and cells with marked pleomorphism ( black arrows ).

Transitional cell carcinoma showing diffuse positivity for WT-1 in the tumor cells.

The most important differential diagnoses are metastatic urothelial carcinoma to the ovary and malignant Brenner tumor (MBT). Clinical history of bladder cancer is essential to exclude metastatic urothelial carcinoma. Histologically, the two tumors are very similar; however, the presence of more typical areas of high-grade serous carcinoma would support an ovarian primary. Immunohistochemically, unlike ovarian transitional cell carcinoma, urothelial carcinomas are positive for CK20, GATA3, and uroplakin (~ 50% of cases), while negative for WT-1 and hormone receptors. PAX-8 can be positive in both tumors.

MBTs usually have infiltrating nests of tumor cells with urothelial-like appearance. The hallmark of the diagnosis is the presence of benign or borderline Brenner tumor, and sometimes extensive sampling is necessary to find these components. MBTs are usually negative for WT-1 and hormone receptors, though the latter may be weakly expressed. The expression of markers of urothelial differentiation such as GATA3 is not well studied currently, limiting its use.

The molecular profile of transitional cell carcinomas is not well-studied due to the lack of consistency in reporting and accurately diagnosing these tumors. A recent study has shown that proteins associated with cell death, apoptosis and necrosis were highly expressed in transitional cell carcinomas (defined as tumors having > 50% of said morphology). Conversely, proteins with reduced expression included those associated with DNA homologous recombination, cell mitosis, proliferation and survival, and cell cycle progression pathways. Proteomic analysis revealed three biomarkers including Claudin-4 (CLDN4), ubiquitin carboxyl-terminal esterase L1 (UCHL1), and minichromosome maintenance protein 7 (MCM7) that were enriched in transitional cell carcinoma over high-grade serous carcinoma, but were not able to distinguish the two tumors with 100% sensitivity and specificity. Additional studies are necessary to confirm these differences and determine their clinical significance.

Like epithelial ovarian cancers, ovarian transitional cell carcinomas are staged according to International Federation of Gynecology and Obstetrics (FIGO) staging ( Table 8.2 ). As there have been so few reported cases of these tumors, there is not much data on overall prognosis and survival. Kommoss et al. found that ovarian transitional cell carcinomas had a significantly better prognosis as compared to all other types of ovarian carcinomas after standardized chemotherapy (5-year survival was 57% as compared to 31% for patients with ovarian carcinomas of other types, P = 0.03). In addition, the authors found that even among patients with postoperative residual tumor < 1 cm, there was still a trend toward better survival. It has also been suggested by other researchers that ovarian transitional cell carcinomas are more chemosensitive than epithelial ovarian cancers and this may explain the better prognosis compared to other more common serous carcinomas. Guseh et al. found that patients with these tumors are less likely to demonstrate resistance to platinum chemotherapy and have improved overall survival when compared to patients with papillary serous ovarian cancer. The authors suggested that a propensity for micronodular rather than macronodular extraovarian spread and better surgical resectability due to lesser degree of diffuse infiltrative growth may also be factors contributing to the overall improved survival and prognosis.

Patients with transitional cell carcinoma of the ovary appear to benefit from optimal surgical resection, followed by adjuvant platinum-based chemotherapy. Given the scarcity of reported cases, there are no current recommendations for surveillance and treatment of recurrence. Because transitional cell carcinomas of the ovary follow a similar tumorigenic pathway to high-grade serous ovarian cancer and have been shown to be associated with better prognosis after following a similar treatment paradigm, surveillance for recurrence and treatment of recurrent disease should be the same as that for epithelial ovarian cancers ( Fig. 8.4 ).

Society of Gynecologic Oncology. Society of gynecologic oncology guidelines for epithelial ovarian cancer surveillance.

Malignant Brenner tumors

MBTs are a rare subtype of epithelial ovarian cancer. Originally identified by Fritz Brenner in 1907, Brenner tumors of the ovary represent < 1% of all ovarian neoplasms. These tumors can be benign, borderline, or malignant. The vast majority of Brenner tumors will be benign or borderline with only 5% malignant. The median age for diagnosis in women with MBTs is 65 years old (range 34–95). This age at diagnosis is older than other epithelial ovarian cancers. For example, the median age at diagnosis for serous ovarian cancer is 60 years old, 58 years old for endometrioid, 55 for clear cell, and 52 for mucinous ovarian cancer. There are no known risk factors for developing these tumors.

MBTs resemble ovarian transitional cell carcinomas and careful pathologic review should be performed to distinguish the two. These two entities were first differentiated in 1987 by Austin and Norris. Although they share similar histologic features, MBTs are generally felt to be low-grade malignancies while transitional cell carcinomas are considered more aggressive high-grade tumors. For diagnosis, MBTs require the presence of both benign and malignant epithelial components with destructive stromal invasion. As described above, in contrast, transitional cell carcinomas resemble urothelial carcinomas and are marked by the absence of any Brenner tumor component.

Tumors are usually unilateral but can occasionally be bilateral with a median size of 10 cm ( Fig. 8.5 ). They may be completely solid or cystic with mural nodules. MBT, by definition, is composed of a frankly malignant component, akin to high-grade papillary urothelial carcinoma, with associated benign or borderline areas ( Fig. 8.6 ). The malignant component comprises of nests of tumor cells with transitional type epithelium that invade the ovarian stroma ( Fig. 8.7 ). The tumor nests can be haphazard with angulated and infiltrative pattern or have a solid growth pattern. The tumor cells usually show nuclear pleomorphism and mitotic activity. Foci of squamous or glandular differentiation may be present. Areas of necrosis are common. In the absence of a benign or borderline component an alternative diagnosis should be considered. In rare cases a coexisting mucinous adenocarcinoma may be present.

Gross image shows a large, solid and cystic yellow mass with hemorrhagic areas.

The morphologic features are akin to high-grade papillary urothelial carcinoma with papillary architecture and marked cytologic atypia.

Areas of solid and invasive growth are often present.

Brenner tumors are positive for cytokeratin, EMA, PAX-8, p63, and GATA-3 while negative for ER, PR, and WT-1. Immunohistochemistry for p53 shows a wild-type pattern of staining. Most exhibit a CK7-positive and CK20-negative profile.

MBT arises from benign and borderline Brenner tumors ( Fig. 8.8 ). Repeated PIK3CA mutations and MDM2 amplification have been reported. In contrast, no mutations have been observed in the TP53 gene or the TERT promoter region, which is frequently seen in urothelial carcinoma.

By definition, an associated benign or borderline Brenner tumor must be present.

The diagnosis of MBT is made only in the presence of benign or borderline Brenner tumor. Tumors lacking a benign Brenner component (previously designated as transitional cell carcinoma) are now regarded as high-grade serous carcinoma with transitional-like features. High-grade serous carcinoma displays a greater degree of cytologic atypia and nuclear pleomorphism with staining for WT-1 and aberrant p53 expression (overexpression or null-type pattern).

Metastatic urothelial carcinomas from the urinary tract are usually associated with a deeply invasive and clinically evident primary tumor. Metastatic disease involving the ovary is usually bilateral and in the form of multiple small nodules with ovarian surface involvement. Urothelial carcinomas are positive for CK7 and CK20 while MBTs are generally negative for CK20.

Women with MBTs may present with abdominal distension or pelvic discomfort although many will be asymptomatic with diagnosis made incidentally after removal of the ovary for other reasons. Although these tumors do not produce or secrete hormones, women may experience dysfunctional uterine bleeding or postmenopausal bleeding. The etiology for bleeding symptoms is unknown. Less than 10% of women with MBT will have ascites at diagnosis and its presence should make the clinician consider other types of epithelial ovarian cancers. That said, if ascites is present and paracentesis reveals squamous cells, there is a higher likelihood that the patient has a MBT.

As with other ovarian neoplasms, CA-125 is the tumor marker most commonly assessed. In one large population-based study, CA-125 was elevated in 70% of women with MBT in whom it was drawn; however, the level of CA-125 level did not seem to correlate with tumor burden. Other studies have reported only 30% to 40% of patients with MBTs as having an elevated CA-125. One report of 2 cases showed that CA 72–4 may be elevated in women with MBT although this is not a commonly used tumor marker.

Imaging work-up should include either a CT scan or MRI. PET scan is unlikely to add useful information beyond CT scan or MRI. Although median tumor size is 10 cm, a large proportion of patients will have small tumors (< 2 cm). Larger tumors will have both solid and cystic components with amorphous calcifications seen in the solid component. In contrast to many other types of epithelial ovarian cancers, MBTs are unlikely to show evidence of hemorrhage or necrosis on imaging.

Staging for MBTs is the same as those for other epithelial ovarian cancers ( Table 8.2 ). Women with MBT tend to present with unilateral ovarian masses (84%). Fifty-five percent will be stage I at diagnosis, while 14% will have stage II disease, 18% stage III, and 12% stage IV ( Table 8.3 ). Histologically, 13% will be grade 1 tumors, 30% grade 2, and 57% will have grade 3 disease.

As the majority of women will present with unilateral, stage I disease, the overall prognosis is quite good ( Table 8.3 ). For these women, 5-year disease-specific survival (DSS) is 95% with 5 year overall survival 69%.The median overall survival for women with stage I disease is 91 months compared to 49 months for those with extra-ovarian disease at diagnosis. Women with low-grade tumors (grade 1 or 2) also have improved DSS compared to those with high-grade (grade 3) neoplasms (94% vs 44%). However, this does not translate to a difference in overall survival although that may just be due to small sample sizes in these studies.

Surgical resection with an attempt at complete cytoreduction is the mainstay of initial treatment for women with MBT. The role of lymphadenectomy (LAD) as part of the initial cytoreductive surgery is unknown. Only 5% of women will have metastatic disease to the lymph nodes and there does not appear to be a survival advantage for those women who underwent LAD compared to those who did not. In addition, there is a low likelihood of nodal disease even when imaging suggests possible metastasis. In one study, 6 out of 10 patients with MBT had preoperative imaging suggestive of nodal disease; however, none of these patients had findings of metastatic disease on pathologic examination of surgical specimens. We recommend resection of suspicious nodes on preoperative imaging or on intraoperative assessment of the retroperitoneum.

Adjuvant chemotherapy with 6 cycles of platinum/taxane regimen should be administered to all patients with stage II-IV disease. In addition, postoperative chemotherapy should be given to women with stage IC disease. For women with stages IA–IB disease, there are limited data on which to base the decision for observation or chemotherapy. In one study, three patients with stage IA/IB were observed. Two women were without recurrence at 47 months (one with stage IA, the other with stage IB) while 1 woman with stage IB disease recurred at 12 months. In another study, 4 women with stage IA disease were observed after surgery. None had recurred at a median follow-up of 75 months. A fifth patient with stage IA disease received postoperative chemotherpay and was without recurrence at 8 months. In one last report of 4 women with stage IA or IB disease, 2 received adjuvant chemotherapy and were without disease at 60 months, one was observed and without disease at 126 months, and one was lost to follow-up. Based on these limited data, we would recommend observation for all women with stage IA MBTs (all grades) and for those with stage IB, grade 1 or 2 disease. For women with stage IB, grade 3 disease, we would recommend adjuvant chemotherapy with a platinum and taxane regimen.

As mentioned, the overall prognosis for women with stage I disease is excellent (5-year DSS 95%) while those with stage II–IV disease have a 5-year DSS of 51% ( Table 8.3 ). Median time to recurrence is 11 months. The most common sites of recurrence are the peritoneal cavity and lung with reports of recurrences in the dura, the skin, and bone.

Treatment for recurrence typically mimics those for other epithelial ovarian cancers with similar agents for platinum-sensitive and platinum-resistant recurrences. Chemotherapy for recurrences is unlikely to be curative; however, there have been reports of long-term survivals even in women with distant recurrences. The role of secondary cytoreductive surgery and radiation are unknown and should be considered on an individualized basis. One patient had a pelvic recurrence after upfront therapy that included bevacizumab maintenance. She underwent secondary cytoreductive surgery followed by pelvic irradiation and was without recurrence at 24 months after treatment. Another patient with recurrence had a good response to radiation followed by cyclophosphamide and doxorubicin.

MBTs are microsatellite stable with low tumor mutational burden so the role of single agent immunotherapy may be limited. These tumors have been shown to have alterations in FGFR3 in 45% of cases. Anti-FGFR inhibitors such as erdafitinib and pemigatinib in recurrent MBTs that harbor these alterations may be considered.

Endometrioid carcinoma

Endometrioid ovarian carcinoma is an ultrarare subtype of epithelial ovary cancer. The first cases of endometrioid ovarian carcinoma were described by Dr. John A. Sampson in 1925, when he described cases that were frequently associated with endometriosis and closely resembling the most common carcinoma of the uterine corpus. Over the subsequent few decades, additional cases were described in individual case reports and small case series.

Endometrioid ovarian carcinoma can be associated with Lynch syndrome, an autosomal dominant syndrome in which a germline mutation in the DNA mismatch repair mechanisms results in an increased risk of carcinogenesis in various organs. It is estimated that patients with Lynch syndrome have a 10% lifetime risk of developing endometrioid ovarian carcinoma, with some variation depending on mutation type. In North American and European populations, the endometrioid subtype accounts for approximately 10% of all epithelial ovarian cancer ( Table 8.1 ). A family history in a first-degree relative has been associated with an increased risk of endometrioid ovarian carcinoma with relative risks ranging from 2.81 to 3.81. These tumors are thought to be primarily derived from progenitor cells in endometriosis that differentiate toward a secretory cell lineage, and 11% to 30% of patients also have a concurrent endometrioid carcinoma in the uterus. The concurrent presence of ovarian cancer with endometrial cancer, also known as synchronous endometrial and ovarian cancer is not a rare clinical entity and occurs in approximately 3% of endometrial cancers. When it comes to grading, grades I and II endometrioid ovarian carcinomas represent approximately 84% to 95% of all cases, and grade III cancers represent the remaining 5% to 16% of cases.

Tumors are usually unilateral and large with a smooth surface. They are variably cystic and solid and may be associated with an endometriotic cyst. Similar to endometrial endometrioid carcinoma, the ovarian counterpart shows a wide spectrum of morphologic patterns. Well-differentiated adenocarcinomas show back-to-back glandular, cribriform, and/or villoglandular growth. Higher-grade tumors show areas of solid growth. In general, the cytologic features are concordant with the architectural grade of the tumor. Squamous, morular, and mucinous metaplasia, as well as secretory change, are often present. Some tumors may also display sex cord-like features or corded and hyalinized morphology.

Endometrioid carcinomas express cytokeratins (with a CK7-positive, CK20-negative profile), EMA, PAX-8, ER, and PR. They are usually negative for WT-1 (positive in ~ 10%) and napsin-A (positive in ~ 8%). The vast majority display a wild-type pattern of p53 staining.

Most ovarian endometrioid carcinomas originate in a background of endometriosis. The molecular alterations are analogous to that of endometrial endometrioid carcinoma, including the WNT/β-catenin signaling pathway ( CTNNB1 mutations, 53%), the PI3K pathway ( PIK3CA ), the MAPK pathway ( KRAS , 33%), and the SWI/SNF complex ( ARID1A , 30%). Molecular subtyping, analogous to that of endometrial endometrioid carcinoma as defined by The Cancer Genome Atlas (TCGA), has been proposed for ovarian endometrioid carcinoma.

Metastatic disease can mimic primary ovarian endometrioid carcinoma, particularly colorectal adenocarcinoma, endometrial endometrioid adenocarcinoma, and endocervical adenocarcinoma. Bilaterality, nodularity, and surface involvement are factors that favor metastases. On the other hand, presence of associated endometriosis, adenofibroma, or borderline tumor supports an ovarian primary. Colorectal adenocarcinoma is characterized by a “garland” pattern of glands lined by cytologically malignant columnar cells surrounding central areas of dirty necrosis. In contrast to endometrioid carcinoma, the majority of colorectal carcinomas display a CK7-negative, CK20-positive profile. SATB2, a marker of colorectal carcinoma, is negative. However, endometrioid carcinoma may show positive staining for CDX2 (typically positive in colorectal carcinomas), particularly in areas of mucinous and squamous differentiation. p16 staining is usually patchy in endometrioid carcinomas and diffuse in endocervical primaries, with the caveat being that a subset of high-grade endometrioid carcinomas may show diffuse staining. Detection of high-risk HPV subtypes indicates a metastasis from the endocervix. Lastly, distinction between synchronous endometrial and ovarian endometrioid tumor versus metastatic disease can be difficult. Morphologic features and immunohistochemical profile may be similar at the two sites. A low-grade, low-stage endometrial tumor, in conjunction with an ovarian endometrioid carcinoma that arises in a background of endometriosis would favor synchronous primaries. On the other hand, a deeply invasive tumor with bilateral ovarian tumors and surface involvement would favor metastasis. Immunohistochemistry for mismatch repair proteins, ARID1A, and PTEN may be helpful if the two sites show contrasting staining pattern. Recent molecular studies have shown that the majority of synchronous ovarian and endometrial endometrioid carcinomas are clonally related.

There is also morphologic overlap between ovarian endometrioid carcinoma with other ovarian primary tumors. High-grade serous carcinomas, particularly those with a solid, pseudo-endometrioid, and transitional (SET) pattern, may mimic endometrioid carcinoma. Immunohistochemistry for WT-1 and p53 are helpful in differentiating the two entities. Cytoplasmic clearing due to secretory change or squamous differentiation in endometrioid carcinoma may mimic clear cell carcinoma. Furthermore, clear cell carcinoma is also associated with endometriosis. Immunohistochemistry for ER, PR, and napsin-A is helpful in this differential. Lastly, sex cord-like features in endometrioid carcinoma may be confused with a sex cord stromal tumor. Areas of conventional endometrioid morphology, particularly the presence of squamous metaplasia, an adenofibromatous component, and the presence of endometriosis are helpful in favoring endometrioid carcinoma. Sex cord stromal tumors often stain with cytokeratin; however, they are almost always negative for EMA and positive for sex cord markers such as SF-1, inhibin and calretinin.

The clinical presentation is similar to that of other epithelial ovarian cancers, including vague symptoms such as abdominal pain, bloating, back pain, and urinary or bowel symptoms. The cancer antigen 125 (CA-125) level at initial presentation is found to vary widely but is most commonly modestly elevated. The differential diagnosis is broad and includes endometrioid adenofibroma, borderline ovarian tumor, dedifferentiated endometrioid carcinoma, high-grade serous carcinoma, clear cell carcinoma, carcinosarcoma, sex-cord stromal tumors, metastatic adenocarcinoma from extragenital sites, glandular yolk sac tumor (YST), and metastatic endometrioid carcinoma from the uterus.

For endometrioid ovarian carcinoma, the WHO classification recommends the same FIGO staging that is applicable for epithelial ovarian cancers ( Table 8.2 ). In cases where synchronous endometrial and ovarian cancers are found, a recent study using next generation sequencing suggests that sporadic synchronous endometrioid endometrial and ovarian cancers are clonally related and likely represent disseminated disease from one site to the other. Therefore, in cases of synchronous endometrial and ovarian cancer, FIGO staging that is applicable for uterine cancer is recommended ( Table 8.4 ). Data from the Surveillance, Epidemiology, and End Results (SEER) showed that the 1-year, 5-year, and 10-year overall survival for localized OEC are 96.9%, 87.1%, and 72.5%, respectively. Stage has been shown to be a significant prognostic factor in endometrioid ovarian carcinoma. Other positive prognostic factors include ER expression (HR = 0.18) and PR expression (HR = 0.22). Lymphovascular invasion, p16-block positivity (HR = 1.88), BAF250a loss, nuclear beta-catenin expression (HR = 2.25), and aberrant p53 expression (HR = 3.41) have been found to be negative prognostic factors. Given the association with Lynch Syndrome and frequent presence of high microsatellite insufficiency (MSI-H) and mismatch repair deficiency (MMR-D), it is reasonable to perform immunohistochemistry for mismatch repair proteins or assess for MSI in these tumors, particularly given implications for effectiveness of checkpoint inhibitors. In fact, Liu et al. found that in 74 cases of ovarian endometrioid carcinomas, 20% of the tumors were microsatellite instability (MSI) high, with at least 2 of 4 microsatellite markers (BAT25, BAT26, D5S346, and D17S250) showing instability.

Table 8.4

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. Ovarian clear cell carcinoma
2. Small cell carcinoma of the ovary, hypercalcemic type
3. Uterine serous carcinoma
4. Other rare uterine sarcomas: Adenosarcoma, endometrial stromal sarcoma, STUMP

Stay updated, free articles. Join our Telegram channel

Join