Clinical Outcomes of Pleomorphic High-grade Squamous Intraepithelial Lesions of the Uterine Cervix: A Single-institutional Experience of 44 Cases

Abstract

Background/Aim

Pleomorphic high-grade squamous intraepithelial lesions (PHSILs) of the uterine cervix are characterized by strikingly pleomorphic and enlarged nuclei with brisk mitotic activity. The aim of this study was to analyze the clinical outcomes of patients with PHSIL.

Patients and Methods

Clinical data were collected from the electronic medical records of 44 patients with PHSIL.

Results

The patients’ mean age was 52.1 years. The initial cytological diagnosis was HSIL in 43.2% of patients. High-risk human papillomavirus was detected in 89.5% of patients. The human papillomavirus type was not predominated by one specific type. The patients were treated with conization alone or with conization with subsequent hysterectomy. Two cases of squamous cell carcinoma coexisting with PHSIL, and one case of adenoid basal carcinoma were detected among the surgical specimens. Follow-up cytology revealed negative results for intraepithelial lesions in all patients, except for one patient who experienced recurrent PHSIL 41 months after hysterectomy and underwent laser ablation.

Conclusion

The incidence rates of concurrent squamous cell carcinoma (4.5%) and recurrence (2.3%) in our PHSIL cohort were lower than those previously reported in patients with conventional HSIL. Our findings suggest that pleomorphic nuclear change alone in PHSIL was not associated with worse clinical outcomes than conventional HSIL and support the notion that PHSIL does not require more aggressive clinical management than conventional HSIL. However, close follow-up with cytological examination may be necessary to determine the potential risk of recurrence.

Despite cytological screening and prophylactic human papillomavirus (HPV) vaccination in developed countries, cervical carcinoma remains a leading cause of carcinoma-related death in women worldwide (1,2). The prognosis of patients with recurrent or metastatic cervical carcinoma remains poor; therefore, novel diagnostic biomarkers and therapeutic strategies for patient stratification are urgently required. Squamous cell carcinoma (SCC) is the most common histological type of cervical carcinoma and accounts for approximately 70% of cases, with some variation observed across different populations (3-5). High-grade squamous intraepithelial lesion (HSIL) is a premalignant cervical lesion associated with a significant risk of developing SCC (6-9). Approximately 10% of HSIL cases progress to SCC within 10 years (10,11). HSILs should be treated properly because they may be a warning sign for SCC.

We encountered dozens of HSIL cases with unusual histological features such as strikingly pleomorphic and enlarged nuclei, brisk mitotic activity, and frequent atypical mitoses. These features are readily identified by scanning or low-power magnification. The term pleomorphic HSIL (PHSIL) was coined for lesions exhibiting marked nuclear enlargement, hyperchromasia, and pleomorphism, often accompanied by numerous mitoses and multinucleation (12). To date, little information is available regarding PHSIL. Only a few studies have documented the clinical significance of PHSIL and referred to this rare variant of HSIL as PHSIL or bizarre cell dysplasia (12-14). In our recent study investigating the clinicopathological characteristics of 31 patients with PHSIL (14), we were not able to analyze the clinical outcomes of PHSIL because of the relatively short follow-up period. In this study, we aimed to analyze the clinical outcomes of a large single-institution cohort of patients with PHSIL for whom long-term follow-up information was available.

Patients and Methods

The study protocol was approved by the Institutional Review Board of Samsung Medical Center (Seoul, Republic of Korea; protocol number: 2024-07-027; date of approval: July 10, 2024). Owing to the retrospective nature of this study, the Institutional Review Board waived the requirement for investigators to obtain signed informed consent. We retrospectively analyzed a consecutive cohort of 44 patients with PHSIL who were treated at Samsung Medical Center (Seoul, Republic of Korea) between March 2019 and August 2023.

The following clinicopathological information was collected from the electronic medical records: Age at the initial diagnosis; HPV status; initial cytological diagnosis; histological diagnosis, based on biopsy, conization, and hysterectomy specimens; the largest dimensions of PHSIL and carcinoma in the conization and hysterectomy specimens; follow-up cytological diagnosis; and post-treatment recurrence. A Board-certified gynecological pathologist (H-S.K.) thoroughly reviewed all available ThinPrep cytology slides (Hologic, Marlborough, MA, USA) and hematoxylin- and eosin-stained histology slides, and confirmed the diagnosis of each case. The cytological diagnosis was established using the 2014 Bethesda System for Reporting Cervical Cytology (15), and was classified as follows: SCC; HSIL; atypical squamous cells, cannot exclude HSIL (ASC-H); LSIL; atypical squamous of undetermined significance (ASC-US); and negative for intraepithelial lesion or malignancy (NILM). Histological diagnosis was established, using the criteria of the Lower Anogenital Squamous Terminology Standardization Project (16) and the 2020 World Health Organization Classification of Female Genital Tumors (17). Patients with PHSIL underwent cytological screening at least 6 months after treatment, and this study included patients who underwent at least one cytological examination following treatment for PSHIL.

Results

Figure 1 shows the typical morphological features of PHSIL. PHSIL is defined by nuclei at least four times larger than those of normal basal cells, with striking nuclear pleomorphism and hyperchromasia (13,14). In agreement with this definition, we noted that the nuclei of PHSIL were at least four-fold larger than those of normal basal cells and adjacent conventional HSIL (Figure 1A). PHSIL frequently displayed expansile involvement of the endocervical glands (Figure 1B). Some cases of PHSIL had small cyst-like spaces containing an admixture of necroinflammatory exudate and parakeratotic cellular debris. Characteristic marked nuclear pleomorphism, increased mitotic activity (Figure 1C), atypical mitoses, and conspicuous nucleoli (Figure 1D) were observed. Some pleomorphic cells possessed variable amounts of clear or eosinophilic cytoplasm, resulting in a lower nuclear-to-cytoplasmic ratio than that of the adjacent conventional HSIL cells. Several areas showed degenerative-appearing chromatin patterns, such as pyknosis, smudging, ground-glass appearance (Figure 1E), and intranuclear cytoplasmic pseudo-inclusions and vacuoles (Figure 1F).

Figure 1.

Histological features of pleomorphic high-grade squamous intraepithelial lesion (PHSIL) of the uterine cervix. (A) Compared with conventional HSIL (white arrows), PHSIL (black arrows) displays significant nuclear enlargement, pleomorphism, and hyperchromasia. (B) The endocervical gland involved by PHSIL has rounded, smooth contours without desmoplastic stromal reaction. An atypical mitosis is indicated with a blue arrow. (C) A higher magnification of part of image A reveals easily identifiable mitotic figures (green arrows) and marked nuclear enlargement (yellow arrow). (D) An atypical mitosis (blue arrow) and a markedly enlarged nucleus (yellow arrow) with conspicuous nucleoli are evident. (E) Some PHSIL nuclei exhibit degenerative-appearing chromatin patterns (orange arrows), including pyknosis and clearing with prominent nuclear membrane (i.e., ground-glass appearance). (F) Intranuclear cytoplasmic pseudo-inclusions (purple arrows). Hematoxylin and eosin staining. Magnification levels: A, 100×; B, 100×; C, 400×; D, 400×; E, 200×; and F, 200×.

Figure 2 presents the flowchart of the participant selection process and clinical consequences. During the study period of 53 months, we collected 55 consecutive cases of cervical PHSIL, identified from our institutional databases. Five patients were excluded from this study because they were lost to follow-up immediately after the diagnosis of PHSIL from their punch biopsy samples. Six patients for whom follow-up information was unavailable were excluded because they were referred to other hospitals after conization (3/6, 50.0%) or total hysterectomy (3/6, 50.0%). Finally, we included 44 patients with PHSIL whose complete follow-up data were available for this study. Thirty-one (70.5%) patients underwent conization only, whereas four (9.1%) patients underwent total hysterectomy only. Six (13.6%) patients underwent conization and subsequent hysterectomy for PHSIL. Two (4.5%) patients (cases 8 and 30) and one (2.3%) patient (case 31) whose SCCs and adenoid basal carcinoma (ABC) were diagnosed from the conization specimens underwent radical hysterectomy.

Figure 2.

Flowchart of the participant selection process and the clinical consequences of pleomorphic high-grade squamous intraepithelial lesions (PHSILs). Forty-four patients were included in this study. Most (41/44; 93.2%) patients had no disease recurrence. Two (4.5%) patients with abnormal results in the first follow-up cytology were diagnosed as negative for intraepithelial lesion or malignancy (NILM) in subsequent examinations. One (2.3%) patient who developed PHSIL recurrence was treated with laser ablation. ABC: Adenoid basal carcinoma; ASC-H: atypical squamous cells, cannot exclude HSIL; ASC-US: atypical squamous cells of undetermined significance; SCC: squamous cell carcinoma.

Table I presents the detailed clinicopathological features and outcomes of the 44 patients with PHSIL. The clinicopathological features are summarized in Table II. The patients’ mean age was 52.1 years (range=29-83 years). The initial cytological diagnoses were HSIL and ASC-H in most (29/44, 65.9%) patients. However, some patients were diagnosed with ASC-US (3/44, 6.8%), LSIL (4/44, 9.1%), SCC (2/44, 4.5%), or NILM (5/44, 11.4%). High-risk HPV was detected in 34 (91.9%) of 37 patients with an available HPV status. Ten (27.0%) patients were co-infected with two or more HPV types. The HPV infection was not predominated by one specific type; the most common types were 16 (10/37. 27.0%), followed by 53 (7/37, 18.9%), 51 (6/37, 16.2%), 56 (4/37, 10.8%), and 33 (3/37, 8.1%). The initial biopsies were diagnosed as PHSIL in all samples, except two (95.2%), which had atypical cells and LSIL. The presence of PHSIL was confirmed in 29 (65.9%) conization specimens, whereas in seven (15.9%) cases, no residual PHSIL was identified. In addition to PHSIL, two (4.5%) cases of SCC and one (2.3%) case of ABC were detected using the conization specimens. The largest dimension of PHSIL measured in the conization specimens ranged from 0.5 to 18.0 mm. Among 13 (29.5%) patients who underwent hysterectomy, the presence of PHSIL, SCC, or ABC was confirmed in 12 patients. The mean largest dimension of PHSIL measured in the hysterectomy specimens was 8.0 mm (range=1.0-20.0 mm). By contrast, the largest dimensions of the SCCs measured in the conization and the hysterectomy specimens of the two patients did not exceed 1.0 mm (i.e., they were stage IA1). Additionally, ABC coexisted with PHSIL in one patient. Although the two lesions were intermingled with each other, PHSIL was located in the superficial cervical stroma while ABC occupied mainly the deep stroma. As a result, ABC was identified both in the hysterectomy and the conization specimens, but PHSIL was observed only in the conization specimen. The largest dimension of ABC was 24 mm.

Table I. Detailed clinicopathological characteristics of 44 patients with pleomorphic high-grade squamous intraepithelial lesion (PHSIL).

ABC: Adenoid basal carcinoma; ASC-H: atypical squamous cells, cannot exclude HSIL; ASC-US: atypical squamous cells of undetermined significance; B: basal; CIN: cervical intraepithelial neoplasia; EN: endocervical; EX: exocervical; HPV: human papillomavirus; HR: high-risk; LSIL: low-grade squamous intraepithelial lesion; NA: not applicable; ND: not detected; NER: no evidence of residual PHSIL; NILM: negative for intraepithelial lesion or malignancy; RFS: recurrence-free survival; SCC: squamous cell carcinoma yr: years

Table II. Summary of the clinicopathological characteristics of 44 patients with pleomorphic high-grade squamous intraepithelial lesion (PHSIL).

ASC-H: Atypical squamous cells, cannot exclude HSIL; ASC-US: atypical squamous cells of undetermined significance; HPV: human papillomavirus; LSIL: low-grade squamous intraepithelial lesion; NA: not applicable; NER: no evidence of residual PHSIL; NILM: negative for intraepithelial lesion or malignancy; SCC: squamous cell carcinoma.

Table III summarizes the outcomes of patients with PHSIL. All patients underwent regular follow-ups with cytological examinations. The mean follow-up period was 30.0 months (range=6-60 months). Most (41/44, 93.2%) patients were diagnosed with NILM in all examined follow-up cytology samples. In two patients (4.5%), the first follow-up cytology was interpreted as ASC-US and ASC-H, respectively, but subsequent samples were diagnosed as NILM. One (2.3%) patient (case 34) developed post-treatment recurrence 41 months after initial diagnosis. The patient was treated with laser ablation for recurrent PHSIL, which was diagnosed via follow-up cytology. A brief presentation of the only recurrent PHSIL case is given as follows.

Table III. Summary of the clinical outcomes of 44 patients with pleomorphic high-grade squamous intraepithelial lesions.

ASC-H: Atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion (HSIL); ASC-US: atypical squamous cells of undetermined significance; LSIL: low-grade squamous intraepithelial lesion; NA: not applicable; NILM: negative for intraepithelial lesion or malignancy; SCC: squamous cell carcinoma. *The subsequent cytological diagnoses were NILM in both patients.

The patient was diagnosed with HSIL during routine cytological screening. A punch biopsy revealed PHSIL with suspected foci of stromal invasion. She underwent conization, and the pathological diagnosis was PHSIL (10 mm) with exocervical resection margin involvement. She decided not to undergo hysterectomy immediately, so the patient was observed closely without any further treatment. After 3 years without recurrence, follow-up cytology revealed recurrent PHSIL. She underwent total hysterectomy with bilateral salpingo-oophorectomy, and the pathological diagnosis was PHSIL (20 mm) with vaginal resection margin involvement. Four months postoperatively, the first post-operative follow-up cytology revealed HSIL. The patient underwent laser ablation for the recurrent vaginal lesions. She was scheduled to undergo additional surgery, either partial vaginal excision or stumpectomy.

Discussion

The presence of pleomorphic tumor cells is generally associated with aggressive clinical behavior. However, the clinical significance of the markedly enlarged, pleomorphic nuclei in HSIL remains unclear. We recently described the clinicopathological features of 31 cases of PHSIL (14). However, we were not able to analyze the outcomes of PHSIL because more than two-thirds of the cases had been recently diagnosed (i.e., <6 months after surgery). In our study, we analyzed the clinical outcomes of 44 consecutive patients with PHSIL who were diagnosed and treated at a single institution over a long-term follow-up period. The patients’ mean age was 52.1 years, which was older than the age (33.2 years) of 19 patients reported by Stewart (12). Nearly all (91.9%, 34/37) cases in our study had a strong association with high-risk HPV infections. Ondic et al. (13) reported that HPV type 16 is predominant in PHSIL. Although HPV16 was also the most prevalent type in our study, other types of high-risk HPV types were prevalent, with multiple HPV types detected in 10 (27.0%) patients. Our findings suggest that PHSIL was strongly associated with high-risk HPV infection, but we were unable to conclude whether PHSIL was associated with any specific HPV type. Further studies using a larger cohort of patients with PHSIL are warranted to clarify the prevalence and distribution patterns of HPV types in these patients.

Previous studies reported the presence of giant bizarre cells or large keratinized cells to be commonly associated with stromal invasion (i.e., concurrent SCC) (18,19). In our study, SCC was observed in two patients; thus, the frequency of SCC associated with PHSIL was 4.5%. The incidence rate of concurrent SCC in patients with PHSIL in our study was lower than that reported by Stewart (12) (3/19, 15.8%) but similar to that in conventional HSIL (2/40, 5.0%) reported in the same study (12). Meanwhile, previous studies documented that no patient with PHSIL developed disease recurrence (12,14). However, in our study, one patient experienced recurrence of PHSIL 41 months after hysterectomy. To the best of our knowledge, this finding is the first reported case of recurrent PHSIL. During a follow-up period of 29.6 months, postoperative cytology revealed NILM in 93.2% (41/44) of patients. The first follow-up cytology results of two patients were ASC-H and ASC-US, respectively; however, subsequent cytology revealed NILM, resulting in an overall recurrence rate of 2.3% (1/44 patients). This recurrence rate was even lower than the rate (4.8%) reported by Tanaka et al. (20), who analyzed the overall rate of relapse after conization in patients with conventional HSIL. We did not include any conventional HSIL cases in our study; therefore, we were unable to compare the clinical outcomes directly between PHSIL and conventional HSIL. Instead, we compared our results indirectly with previous data. The frequencies of concurrent SCC and recurrent disease in PHSIL were not higher than those observed in conventional HSIL, suggesting that clinical outcomes were not significantly worse with PHSIL than with conventional HSIL. Our observations supported the notion that the pleomorphic cytological appearance in HSIL is not necessarily correlated with aggressive clinical behavior (12). However, one patient developed recurrence after a long period. This patient had resection margin involvement in the conization specimens and hysterectomy specimens. The size of the PHSIL was 20 mm, which was the largest among the cases included in our study. If a large PHSIL involves a resection margin in the conization specimen or hysterectomy specimen, close follow-up with cytological examination is necessary to observe for the potential risk of recurrence.

We provide the first report of a case of coexistence of ABC and PHSIL. It is well known that ABC is commonly accompanied by HSIL (17). However, no case of ABC coexisting with PHSIL has been reported to date. ABC measured more than 20 mm, but the patient did not experience tumor recurrence 12 months after hysterectomy, supporting the notion that ABC exhibits excellent prognosis with very low or no potential for metastasis and recurrence (17).

Study limitations. This study had several limitations. Firstly, we primarily focused on the clinical characteristics of PHSIL and did not perform immunostaining. Previous studies reported that all PHSIL specimens have strong and diffuse immunoreactivity for p16 and p63 (12,14). We recently demonstrated that the Ki-67 labeling indices differ between PHSIL cases involving both the surface and the glands and those involving only the surface (14). Immunostaining for these markers and a comparison of their expression between the two entities may better characterize PHSIL and provide additional prognostic information. Secondly, this study was conducted at a single institution, which limits the reproducibility of the results. Patient demographics, clinical manifestations, and management strategies may vary between institutions and regions. Additionally, the small sample size may not adequately represent the diversity of perspectives, although the sample size in this study was larger than those in previous studies. Therefore, future investigations with larger multi-institutional cohorts of patients with PHSIL are warranted to validate our findings and encompass the full spectrum of clinical behaviors and outcomes of PHSIL. Finally, the retrospective nature of this study may have intrinsic biases related to data collection and patient selection. Future studies addressing these limitations will help improve diagnostic strategies and clinical management of PHSIL.

Conclusion

We analyzed the clinical outcomes of 44 consecutive patients with PHSIL who were diagnosed and treated at a single institution. The patients were treated with conization alone or treated with conization and subsequent hysterectomy. Two patients were diagnosed with stage IA1 SCC and coexisting PHSIL. We herein describe the first case of ABC coexisting with PHSIL. To date, all patients, except only one who developed recurrent PHSIL (41 months after hysterectomy), remain alive without disease recurrence. Compared with the previously reported recurrence rate of conventional HSIL, our findings suggested that pleomorphic cell morphology alone in PHSIL is not associated with worse clinical outcomes. Based on these results, our data support the previous notion that pleomorphic HSIL does not require a more aggressive clinical management than that of conventional HSIL. However, close follow-up with cytological examination is necessary to determine the potential risk of recurrence.

Conflicts of Interest

All Authors have no conflicts of interest or financial ties to declare that are relevant to the content of this article.

Authors’ Contributions

All Authors made substantial contributions to the conception and design of this work, acquisition and interpretation of data, drafting and critical revision of the article for important intellectual content, and gave approval of the final version to be published.

Acknowledgements

This work was supported by a Samsung Medical Center Grant (SMO1240641) and a National Research Foundation of Korea (NRF) grant funded by the Korean Government (MSIT) (2023R1A2C2006223).