Adenoid cystic carcinoma of the vulva: A case report and literature review

Introduction

Adenoid cystic carcinoma (ACC) of the vulva is a rare and aggressive malignant tumor that typically originates from the Bartholin gland located near the vaginal introitus. Bartholin gland carcinoma accounts for <1% of gynecological cancers and 3–7% of all vulvar malignancy (2). In the vulva, ACC is a rare malignancy that was represents ~30 % of Bartholin gland carcinoma (2) and was first described by Bernstein et al (3) as a rare histological subtype of adenocarcinoma, affecting mainly the glandular mucosa, salivary glands, mammary glands and the female genital tract, particularly the cervix. Due to its rare occurrence (4) and non-specific clinical manifestations, the disease is easily misdiagnosed as a Bartholin gland cyst and abscess. (1,5). Risk factors may be associated with chronic inflammation, abnormal hormone levels, etc. (6). In addition, treatment methods mainly include surgical excision, radiation therapy, and chemotherapy, but due to the lack of standardized treatment protocols, clinical effects are often inconsistent. The overall 10-year survival rate is 64% (7), underscoring the challenges in managing this rare and complex disease.

Case report

The patient was a 45-year-old Chinese female who underwent regular physical examinations and had no notable past medical history., with menarche at 13 years, having had five pregnancies and one delivery, and with no family history of disease, smoking or drinking. The patient presented with a subcutaneous mass in the right vulvar area that had slowly enlarged over 4 months without pain. The patient had sought medical attention at Central Hospital, Tianjin University in January 2025, due to continuous pain from the mass for 3 days. Upon examination, the skin showed no damage, redness or swelling. Gynecological examination revealed a subcutaneous mass on the right vulva, measuring ~2×1 cm in size. The mass was hard in texture, with mild tenderness and unclear boundaries. As a vestibular gland cyst could be excluded due to clearly defined boundaries, further examination of the patient was conducted. The patient was negative of human papillomavirus (HPV) and tested positively for syphilis. Alanine aminotransferase (ALT) was 30 U/l and aspartate aminotransferase (AST) was 25 U/l, with the normal reference range for both typically being 0–40 U/l. Total bilirubin (TBIL) was 10 µmol/l (normal reference range of <34 µmol/l. Serum creatinine (Cr) was 50 µmol/l, with a normal reference range for females of 44–97 µmol/l. Blood urea nitrogen (BUN) was 7 mmol/l, with a normal reference range typically being 2.9–8.2 mmol/l. Carbohydrate antigen 125 (CA125) was 10 U/ml (reference range typically <35 U/ml. Ultrasound examination showed a heterogeneous echogenic nodule measuring 2.4×1.4×0.9 cm, subcutaneously located on the right vulva, which had uneven internal echoes and blood flow signals visible on the inner edge (Fig. 1). Due to the presence of pain, hard texture, uneven ultrasound echoes and visible blood flow signals, malignancy could not be excluded. The patient underwent surgery on the following day after the initial consultation. The procedure performed was extended local excision. The specific operational steps were as follows: Under local anesthesia, the surgeon excised the lesion along with a surrounding margin of normal tissue using an electrosurgical knife to ensure negative surgical margins. The entire procedure lasted 1 h and 10 min. The resected tissue specimen was sent for pathological examination.

Figure 1. Ultrasound examination (A) Ultrasonography showed a 2.4×1.4×0.9 cm inhomogeneous echogenic nodule (arrow), subcutaneously located on the right vulva. (B) Internal echo was uneven and dot-and-strip blood flow signals (arrow) were visible at the inner edge.

Pathological examination revealed a gray-brown nodular tissue measuring 3.0×1.5×1.4 cm. The section was gray-white with a solid hard consistency. Microscopic observation showed tumor cells composed of glandular epithelial cells and myoepithelial cells (arranged in a cribriform or tubular pattern), with some areas exhibiting a solid growth pattern. Various sizes of clear or basophilic mucinous deposits were observed in the glandular cavities and cribriform structures (Fig. 2A). Accompanying perineural invasion (Fig. 2B) and skeletal muscle invasion could be observed at the invasive front of the tumor (Fig. 2C), with residual Bartholin gland tissue in the surrounding local area (Fig. 2D), considered to be of Bartholin gland origin. No cancer was found at the margins of the tumor. The shortest distance was >1 cm. Tissue specimens were fixed in 10% neutral buffered formalin at room temperature for 8 h, followed by paraffin embedding. Sections of 5 µm thickness were prepared. For detection, sections were first deparaffinized in xylene and rehydrated through a descending alcohol series (100, 95, 80, 70%) to distilled water. Subsequently, heat-induced antigen retrieval was performed by immersing the sections in citrate buffer (pH 6.0) and heating at 95–100°C for 15–20 min. After natural cooling to room temperature, the sections were washed with PBS). CK5/6 (Cat. No.: M7237, Supplier: DAKO), CK7 (Cat. No.: M7018, Supplier: DAKO), P63 (Cat. No.: CM163A, Supplier: Biocare Medical), and KI-67 (Cat. No.: M7240, Supplier: DAKO) were incubated at a dilution of 1:100 overnight at 4°C; S100 (Cat. No.: Z0311, Supplier: DAKO) and GCDFP-15 (Cat. No.: MAB-0240, Supplier: Maixin Bio) were incubated at a dilution of 1:200 overnight at 4°C. For the negative control, PBS was used to replace the primary antibodies. A ready-to-use horseradish peroxidase (HRP)-labeled anti-mouse/rabbit universal secondary antibody (Cat. No.: K5007, Supplier: DAKO) was applied at 1:200 and incubated for 30 min at room temperature. Color development was performed using DAB, followed by counterstaining with hematoxylin for 5 min at room temperature. Observation by light microscopy showed positive CK5/6, CK7, P63 and KI-67 (~20%) staining, and negative S100 and GCDFP-15 staining (Fig. 3A-D). A follow-up ultrasound examination conducted 2 weeks post-surgery showed no significant masses in the bilateral groin superficial lymph nodes (data not shown). Visible lymph nodes did not exhibit abnormal blood flow signals, suggesting reactive hyperplasia. Transvaginal Doppler ultrasound examination revealed no notable abnormalities in the uterus, cervix or bilateral adnexa. Computed tomography scans showed no markedly enlarged lymph nodes in the abdominal or pelvic cavities. Enhanced pelvic magnetic resonance imaging scans revealed multiple lymph nodes in both pelvic walls and bilateral groin areas, some of which were enlarged, with the largest measuring 1.4 cm, with a regular shape and without abnormal blood flow signals. No groin lymphadenectomy was performed, nor was adjuvant radiotherapy or chemotherapy administered (data not shown). The follow-up protocol was clinical examinations conducted every 3 months, with MRI every 6 months for 2 years and annually thereafter. No recurrence of tumors or lymphadenopathy was observed 6 months post-operation. The patient recovered well after surgery and was clinically healthy as of January 2026.

Figure 2. Representative histopathological images of the tumor. (A) Transparent or basophilic mucoid material was deposited within the lumens and varying sizes of sieve-like pores. (B) There was evidence of perineural invasion and (C) skeletal muscle invasion was detected at the leading edge of tumor infiltration. (D) Residual Bartholin's gland tissue was present in localized areas surrounding the tumor. Scale bar, 200 µm).

Figure 3. Representative immunohistochemical images of the tumor. (A) CK7(+), (B) CK5/6(+), (C) P63(+), (D) KI-67(~20%). +, positive. Scale bar, 200 µm).

Discussion

The present review searched PubMed (pubmed.ncbi.nlm.nih.gov/)for case reports on ACC of the vulva in the past 5 years and obtained the references listed in each article. The literature review is summarized in Table I. We identified 12 articles reporting on 36 patients.

Table I. Literature review of ACC of the vulva cases in the past 5 years.

Table I.

Literature review of ACC of the vulva cases in the past 5 years.

First author/s, year	Age, years	Location	Size, cm	Lymph node Involvement	Resection margin	Perineural invasion	Treatment	Relapse and follow-up status	(Refs.)
Evin et al, 2023	31	RV	3.3	-	+	+	LE, RHV, ARTx	PD, 38 months lung; 36 months AWD	(20)
Nieuwenhuyzen-de Boer et al, 2020	61	RV	1	-	+	+	LE, RHV, IILND	Simultaneous lung metastasis	(26)
Güral et al, 2024	56	V	Nts	-	-	+	HV, BILND, ARTx	48 months lung and right humerus; 98 months DOD	(21)
Samba et al, 2024	42	V	Nts	-	-	-	RHV, BILND, ARTx	NED	(23)
	43	LV	Nts	-	+	+	LE, HBSRC, ARTx	60 months NED
	38	V	3.5	Nts	+	Nts	ELE, ARTx	8 months NED
	52	RV	2	-	-	Nts	ELE, BILND, ARTx	36 months NED
Alhashemi et al, 2023	64	LV	7	Nts	Nts	Nts	LE, ARTx	12 months local	(5)
Wang et al, 2022	58	LV	3.2	-	-	-	HV, IILND	18 months NED	(11)
Santiago et al, 2021	77	RV	5	-	-	+	ELE, ARTx	24 months lung; 36 months DOD	(17)
Verta et al, 2022	42	VA	3.4	-	-	Nts	PC+RA, BILND	8 months NED	(6)
Nakamura et al, 2020	63	V	Nts	Nts	-	Nts	LE	4 years lung, 5 years local	(13)
Doutel et al, 2024	61	V	Nts	Nts	-	Nts	TPR	2 years lung and liver	(27)
	52	LMA	2.3	Nts	Nts	+	LE	3 years NED
Zhu et al, 2020	41	BG	5	Nts	-	+	LE, ARTx	Local and lung; 82 months AWD	(28)
	41	BG	Nts	Nts	+	+	LE, ARTx	Multiple metastases (lung, bone, liver); 27 years AWD
	70	VA	0.5	Nts	+	-	LE	129 months AED
	58	LMA	Nts	Nts	+	Nts	LE, ARTx	13 years and 4 months AED
	63	RV	1.5	-	-	+	RLE, IILND	76 months NED
	50	RV	2.1	Nts	+	+	RLE, CT	Local; 74 months SD
	59	LV	3	Nts	+	+	RLE, ARTx	73 months NED
	40	LV	1.5	-	-	+	RHV, IILND	44 months NED
	54	RV	1.2	-	-	+	RLE, IILND	34 months NED
	71	LV	3	Nts	-	+	RLE	30 months NED
	62	LV	2.2	Nts	-	+	RLE	29 months SD
	37	LV	1.5	-	+	+	RLE, IILND, ARTx	NED
	40	RV	3	Nts	+	+	RHV, ARTx	54 months NED
	59	LV	2.5	Nts	-	+	RLE	46 months NED
	57	RV	1.6	Nts	-	+	RLE	37 months NED
	69	RV	1.8	Nts	-	+	RLE	24 months NED
	61	RV	3	-	+	+	RLE, IILND, ARTx	23 months NED
	51	LV	2.5	-	+	+	RLE, IILND, ARTx	NED
	26	LV	1.8	Nts	-	+	RLE	NED
	56	LV	2.8	Nts	-	+	RLE	NED
	50	RV	2	-	-	+	RLE, IILND	78 months NED

[i] RV, right vulva; LV, left vulva,; LMA, labia majora; VA, vagina; ELE, extended local excision; LE, local excision; RV, radical vulvectomy; RHV, radical hemivulvectomy; PC + RA, partial colpectomy + rectal amputation; IILND, ipsilateral inguinal lymph node dissection; BILND, bilateral femoral lymph node dissection; ARTx, adjuvant radiotherapy; CT, chemotherapy; SD, stable disease; NED, no evidence of disease; AWD, alive with disease; DOD, died of disease; Nts, not stated; N, negative; P, positive.

Regarding clinical features, the median onset age for vulvar ACC is 48 years, with an age spectrum ranging from 25 to 80 years, and similar incidence rates in younger and older patients (7). The predominant clinical manifestations are similar to those of salivary gland ACC, marked by a gradually enlarging mass accompanied by discomfort, characterized by a firm texture and indistinct margins, often adherent to surrounding tissues (8). Tumor cells proliferate along the bundles of peripheral nerve fibers, which not only increase surgical complexity but frequently leads to postoperative pain and numbness due to nerve impairment (9). Vulvar ACC exhibits notable invasiveness, with advanced cases often accompanied by local recurrence and distant metastasis; the lungs emerge as the most common sites of distant metastasis, although the involvement of bones, liver and brain has also been reported (9).

The pathogenesis of vulvar ACC includes: i) Hormonal fluctuations during pregnancy, which may influence cell proliferation and differentiation within vulvar tissues, thereby increasing the risk of cancer; however, the precise mechanisms demand further exploration (6); ii) viral infection, as HPV infection is predominantly associated with cervical squamous cell carcinoma and vulvar squamous cell carcinoma (10); however, HPV infection itself does not directly induce vulvar or cervical ACC (11) and the present case was negative for HPV; and iii) genetic mutations and chromosomal irregularities, including the presence of the MYB-NFIB fusion gene, which has been suggested in previous studies (11,12). Additional mutations such as KRAS and KDM6A have also been identified in vulvar adenocarcinoma, with cytogenetic assessments revealing complex karyotypes involving chromosomes 1, 4, 6, 11, 14 and 22 in Bartholin gland adenocarcinoma. These mutations may facilitate tumor development by impacting cell proliferation, differentiation and apoptosis (12,13).

Regarding the pathological diagnosis, histologically, ACC arising from the Bartholin gland is indistinguishable from its counterparts in salivary glands, upper respiratory tract or skin. In regard to its cellular characteristics, it is composed of glandular epithelial and myoepithelial cells. Concerning its histomorphological features, the tumors exhibit tubular, sieve-like or solid growth. The sieve-like arrangement of glandular structures is its typical feature, containing true and false glandular structures (14). True glandular cavities are formed by myoepithelial cells surrounding glandular epithelial cells, whereas false glandular structures are surrounded by myoepithelial cells, with sieve pores appearing round or oval (7). The tubular type is characterized by round or elongated tubular structures lined by epithelial and myoepithelial cells (14). Perineural infiltration is an important feature of vulvar ACC (14). Immunohistochemical markers support epithelial and myoepithelial differentiation, including epithelial markers such as CK and epithelial membrane antigen and myoepithelial markers such as CK5/6, P63, P40, S-100, smooth muscle actin, carcinoembryonic antigen and CD117 (7). ACC of the vestibular glands is extremely rare. To diagnose primary vestibular gland ACC of the vulva, it is essential to exclude ACC that has metastasized from the salivary glands, lacrimal glands, nasopharynx, mammary glands, skin or cervix. The tumor should be located in the Bartholin gland area, and there should be a transitional zone between benign Bartholin gland tissue and the tumor (15,16). Other tumors should be excluded, such as the more common squamous cell carcinoma and adenocarcinoma tumors. Basaloid squamous cell carcinoma primarily has solid structures without cystic cavities or basal membrane-like substances, with focal keratinization observed. In situ squamous cell carcinoma is calponin negative (14). Compared with ACC, adenocarcinoma lacks consistent acinar structures, and there is no basal membrane-like material within the lumen (5,11). Metastatic carcinoid tumors and small cell carcinoma are solid masses, with rare glandular cavities, containing argentaffin cells, and the majority are positive for neuron-specific enolase (14). Carcinoid tumors almost universally express CgA and other neuroendocrine markers (14). This often requires a comprehensive judgment based on clinical history, imaging studies and immunohistochemical markers (8). Genetic testing is essential in diagnosing vulvar ACC, detecting MYB-NFIB fusion genes, other relevant gene mutations and possible genetic susceptibility genes aids in establishing an accurate diagnosis and differentiation of tumor types, providing a basis for personalized treatment plans (11,12,17).

As a rare and highly invasive malignant tumor of the vulva, currently no consensus has been yet reached on the recommended treatment for ACC. Thus, the general consensus on vulvar cancer (18) applies, including radical surgery, which is the main treatment for vulvar ACC, and aimed at achieving complete cure through extensive excision of tumor tissue (3,6). Ensuring sufficient negative margins during surgery is essential in preventing postoperative recurrence; patients with negative margins have a survival time 15–30 years longer than those with positive margins (7). For patients with positive margins, postoperative adjuvant radiotherapy is often recommended to reduce the risk of local recurrence (19–21). The role of lymphadenectomy in the treatment of vulvar ACC remains controversial. Since this tumor rarely metastasizes to groin lymph nodes, not all patients require lymphadenectomy. However, for patients with clinically or radiologically suspected lymph node metastasis, systemic lymphadenectomy is still necessary. Radiotherapy serves an important role in the treatment of vulvar ACC, particularly in patients with positive margins or those who cannot undergo complete surgical excision. Radiotherapy can effectively control local lesions, reduce the risk of recurrence and may improve patients' quality of life. Chemotherapy is predominantly employed for patients exhibiting advanced or recurrent metastatic conditions, with the objective of inhibiting the proliferation and migration of tumor cells through systemic intervention. However, due to the infrequency of vulvar ACC, a standardized chemotherapy protocol remains elusive, necessitating a tailored approach to treatment that is contingent upon the individual circumstances of the patient (22,23). Regarding targeted therapy, a number of ACC cases exhibit expression of the c-Kit receptor (also known as CD117), with the tyrosine kinase inhibitor imatinib emerging as a targeted therapeutic agent aimed to block the c-Kit signaling cascade (24). In phase II clinical trials investigating salivary gland ACC, imatinib has demonstrated efficacy in preventing disease progression (25), while its implications for vulvar ACC warrant further exploration.

A previous study reported the overall recurrence rate of Bartholin's gland ACC as 30% (7), with the simple resection group having a higher recurrence rate compared with the R0 resection group (26 vs. 7%). The recurrence rate for patients with positive margins was 35%, and the metastasis rate was 50%. For the negative margin group, the recurrence rate was 10%, and the metastasis rate was 24%. The distant metastasis rate was 31%, with bone and lung being the main metastatic sites. The effects of chemotherapy varied, with a few patients showing positive responses. The overall 10-year survival rate was 64%, and the median survival time for patients with negative margins (31 years) is significantly longer compared with that of patients with positive margins.

This case underscores the importance of maintaining a high index of suspicion and performing timely biopsy for persistent or slowly enlarging painful vulvar masses in middle-aged and older women . From pathogenesis perspective, the patient in this case was positive for syphilis infection. While previous research has predominantly focused on the role of HPV, existing evidence suggests that Bartholin's gland ACC may be unrelated to HPV infection (26). Molecular pathological studies (11–13) have untangled the potential genetic basis of vulvar ACC. Although the classic MYB-NFIB fusion gene appears less common at this site compared to salivary glands, MYB gene rearrangements and mutations in genes such as KRAS and KDM6A have been reported, which may drive tumor initiation and progression (27). Despite the presence of perineural invasion and skeletal muscle involvement, extended local excision alone was chosen given the negative surgical margins and the absence of clinical or radiological evidence of lymph node metastasis. This approach aligns with the view that surgery alone may be sufficient for early-stage cases with negative margins (28). Regarding inguinal lymph node dissection, its necessity remains controversial. Routine prophylactic dissection may not be mandatory (29). For metastatic or recurrent disease, precise radiotherapy techniques such as stereotactic ablative radiotherapy have shown potential value (30). In the future, with a deeper understanding of the molecular characteristics of the tumor, targeted therapies against specific targets (CD117) may provide new options for patients with advanced disease.

Acknowledgements

Not applicable.

Funding

Funding: No funding was received.

Availability of data and materials

The data generated in the present study may be requested from the corresponding author.

Authors' contributions

ZD conceived and designed the study, acquired patient imaging and pathological images, was responsible for data collection, organization, and contributing to writing the paper. ZD and GL interpreted the data. ZD, GL and CZ reviewed and edited the manuscirpt. CZ was responsible for designing the study, providing recommendations for patient treatment plans, and contributed to overseeing the overall work of the research team. All authors agree to take responsibility for all aspects of the research and ensure that appropriate investigations and resolutions are made regarding the accuracy or completeness of any part of the work. All authors have read and approved the final version of the paper. ZD, GL and CZ confirm the authenticity of all the raw data.

Ethics approval and consent to participate

Not applicable.

Patient consent for publication

Written informed consent was obtained from the patient for the publication of the present case report and relevant images.

Competing interests

The authors declare that they have no competing interests.

References