Among different malignancies in the classification of basaloid lesions of the uterine cervix proposed by Grayson and Cooper , there was a spectrum of basaloid carcinomas which were stated of histopathologic similarities. Many literatures of ABC have focused on diagnostic distinction from other mimicked aggressive malignancies such as ACC, BSCC and small cell (neuroendocrine) carcinoma and to elucidate its histopathogenesis. Meanwhile some reports also revealed valid evidences of the associated malignancy within morphologically pure ABC [4–17]. Since this association was initially documented in 1971 , most of the associated malignancies have been reported mixedly with pure ABCs in the early literatures. The concept of co-existence was then clarified by the divergent epithelial differentiation of the ABC lesion producing associated squamous, adenosquamous or rarely adenomatous malignant components which support the histogenetic pluripotent reserve cell origin of ABC . The co-existing ABC with occasionally identified transitional areas to other malignancy mainly ACC, also showing the potential precursor concept [5, 9]. Additionally, an associated malignancy could occur by the co-incidence of transformed tumor by the common pathogenetic high-risk human papillomavirus (HPV) integration in both components [10–12]. Although the precise frequency of these rare co-existences is hampered by the selection bias on the case-report evidences, it has shown a substantial account  and thus stresses the significance of careful approach with a suspect of associating malignancy in any provisional diagnosed ABC.
Recently, including our case, there are total 98 reported morphologically diagnosed ABCs [1–19]. Apart from the pure lesions, there are 27 cases (27.5%) described by ABC associated with other invasive malignancy in a single neoplasm. Regarding to this review, we firstly determine the common clinicopathological features of these specified cervical co-existent tumors which were sequentially summarized in the Additional File 1 table 1. Most of the patients were menopausal non-Caucasian women. The mean age was 66.7 years (44-84). The most frequent co-existing histology was SCC which accounts for 12 cases, ACC as second most found was co-existed in 9 cases while only 2 associated adenocarcinomas had been specified.
Typically, pure ABCs are asymptomatic, frequently presented by abnormal Pap smear which often associated with high grade squamous intraepithelial lesions (> 90%) [5, 18]. These patients have been successfully treated by non-radical surgery such as simple hysterectomy without documented recurrence or tumor-related death. While if associated with other malignancy, 11 (52.6%) in 19 assessable presentations were asymptomatic with abnormal cervical cytology and most of these had no gross cervical lesion, implying that an associated invasive carcinoma is possibly presented by inactive clinical features. Two patients with co-existent malignancy including our case reported malignant cytology which less likely occurred in the pure ABC group. Moreover, even on comprehensive colposcopy, unusual ulcerative lesion of ABC or other infiltrative malignancy may not be detected. Thus, a cone biopsy is recommended to cover the most represented site of entire cervical tumors . It was recorded that this procedure yielded a high definite diagnosis rate for the co-existent malignancy especially for these asymptomatic undetectable mass patients (6 in 9 patients, 66.6%). Comparing this data, the reviewed co-existent cases with a cervical mass at the presenting time showed its poorer outcome. It would be explained by undiagnosed associated SCC component resulted from an only cervical biopsy and inadequate treatment course for the real status of the associated invasive carcinoma.
In the LEEP specimen, only a focus of microinvasive SCC overlying multiple small nests of ABC was diagnosed. Suggesting that theoretically, area of true invasive carcinoma may not represent in all tumor area or generally admixed with ABC component, but can produce a distinct infiltrate through the deep part of stroma [1, 12] and that resulted in possibility of inadequate assessment by an excisional biopsy. The endocervical resection margin which markedly positive mostly by ABC indicated that we could not exclude a hiding admixed ACC or a further invasive SCC accompanied in the remaining cervix and a repeat conization would be recommended . Considering small residual cervix in the after-conization menopausal patient, a re-conization may be at risk of accidental injury to bladder or rectum with remarkable bleeding or subsequent infection . High accuracy imaging to detect cervical tumor or local invasion by MRI (77-90% accuracy)  was a reasonable option and was again proved by our case. Also with concern on a risk of para-aortic lymph node spreading at a rate of 2-4% for this clinical stage IB1 cervical cancer , we additionally performed para-aortic lymph node dissection at the time of radical hysterectomy, bilateral salpingooophorectomy and pelvic lymph node dissection. The final revealed co-existence compiling ABC associated with truly invasive SCC supported our idea to treat this initially indefinite invasive diagnosed patient as a patient with locally invasive malignancy instead of doing simple hysterectomy which is described as the recommended operation for a typical ABC or even with microinvasive SCC.
The pathological diagnosis was obtained by a matching with the described morphologic criteria based on the current World Health Organization histological classification of tumors of the uterine cervix . The infiltrating foci of the ABC component showed typical small uniform basaloid cell nest without desmoplastic stromal reaction. Squamous differentiation was diffuse and more frequently detected at the superficial area and focal area adjacent to the SCC component, forming cellular transition to the associated carcinoma [4, 9]. These histomorphological findings were clearly distinct the ABC component from the other tumors with basaloid feature like ACC and BSCC which commonly presented with high nuclear pleomorphism, mitotic figure and cribriform or solid growth pattern . Occupying at the most central part of tumors was the invasive squamous component which was deeply infiltrating tumor composed of larger nests of pleomorphic large, non-keratinized squamous differentiated cells with severe nuclear atypia and frequent mitotic features. Obviously this tumor presented a high growth appearance and highly invasive pattern by showing central necrosis and extensive stromal desmoplastic reaction respectively . The result of p63 stain was typical in our case  which showed diffuse expression in both ABC and SCC components intensively by the palisading basaloid cells and suprabasal squamous differentiated cells in the central area of the superficial nests, while markedly reduced reaction in focal glandular (adenoid) differentiated area. The selective Bcl-2 positive reaction in basaloid tumor and SCC shown in our sections helpfully confirmed the basaloid squamous histogenesis and supported their neoplastic natures by showing anti-apoptotic genetic alteration in both components . Moreover, for the cell cycle activity correlated Ki-67 stain which generally reduced expression in the basaloid and adenoid area [16, 17], it was similar to our low index for ABC component and different to a well-defined stronger Ki-67 expression by SCC component. This was implied to higher proliferative activity and indicated distinct malignant potential of the invasive SCC, which corresponded to the central necrosis finding observed on the morphologic exam.
Likewise report of pure ABCs, almost all patients in co-existence group were clinically stage I which primarily treated by a type of hysterectomy. Along with 19 sufficient treatment data, the specific treatments were prescribed mostly depend on nature and stage of the revealed associated invasive malignancy either before or after primary surgery. Obviously different from the pure ABCs, only 3 co-existent cases (15.7%) have been treated by exclusively non-radical hysterectomy. Postoperative adjuvant therapies mainly by radiation were given to 5 cases (26.3%) with 2 of these had received adjuvant treatment after inadequate simple hysterectomy. This data would suggest that a primary radical treatment according to the extension of associated malignancy formally by radical hysterectomy with lymphadenectomy  should be recommended and may prevent unnecessary exposures to radiotherapy and/or chemotherapy.
Including our case with 6 months disease-free interval after postoperative chemoradiaton, the reviewed treatment outcomes of the ABC with associated malignancy patients had mean follow-up time of 31.1 months (0-120) with no evidence of disease in overall 13 of 20 retrievable cases (65.0%). Unlike the favorable outcome of pure ABCs, recurrences were found in 4 cases (20.0%) and 3 of these died of disease.
An invasive malignancy may simultaneously associated with any cervical ABC, that need an adequate diagnostic cone biopsy which can provide clear diagnosis and would serves both needs of proper radical therapy if a likely ABC with co-existent malignancy is diagnosed and also to prevent the over treatment of a pure ABC. Occasionally, if indefinite tissue diagnosis, an acceptable diagnostic option like MRI may be in preference. Through a decision with suspicious occult invasive carcinoma, the primary radical surgery should be considered. In advance, proper adjuvant treatment such as post-operative radiotherapy would be suggested according to the extent of the associated invasive malignancy.