Cowden Syndrome and Oral Lesions: A Case Report Using MLPA

Introduction

Phosphatase and tensin homolog (PTEN) is a tumor-suppressor gene situated on a specific chromosome – 10q22-23. Approximately 60–90% of pathogenic variants of the gene are heritable; Cowden (CS), Bannayan-Riley-Ruvalcaba (BRR), Lhermitte-Duclos (LD), and autism-macrocephaly syndromes are considered to be diseases with pathogenic germline PTEN variants whose expression may be related to penetrance [1,2]. CS and BRR syndromes are the most commonly reported conditions induced by alterations in the PTEN gene. Both are characterized by multiple hamartomas and have overlapping features [3].

Cowden syndrome, which is an autosomal dominant disorder characterized by hamartomas affecting organs derived from any of the 3 germ layers [2], was first characterized in 1963 by Lloyd and Dennis in a 20-year-old woman with adenoid facies and multiple systemic disorders associated with familial inheritance and breast cancer [4]. CS is characterized by oral papillomatous papules, mucocutaneous neuromas, facial trichilemmomas, acral keratosis, and macrocephaly [4,5]. Histopathological examination of oral lesions, clinical manifestations, family history, and genetic studies using MLPA are diagnostic aids in the confirmation of CS that allow development of an ideal treatment plan for each patient [6,7]. In terms of clinical manifestations, it is important to highlight that about 80–90% of patients present adenoid fascia and papillomatous papules in the lip region and oral cavity, which usually become malignant. Therefore, it is important to confirm the clinical diagnosis of papules with a histopathologic study, genetic study, and family medical history [4,6].

Additionally, CS patients may experience various visceral organ involvements, including thyroid abnormalities, breast cancer, endometrial cancer, renal cell carcinoma, and gastrointestinal polyps [8]. This case report highlights the long-standing issue of underdiagnosed oral lesions over a 12-year period in a patient with Cowden syndrome, which was ultimately diagnosed by our oral pathology and medicine service.

Case Report

A 35-year-old woman presented to the Department of Pathology and Oral Medicine of the University Center for Health Sciences (CUCS UdG), where she reported the presence of multiple asymptomatic papules on the jugal mucosa and tongue (Figure 1A–1C), which she had noticed for 12 years. An intra-oral clinical examination revealed multiple papules, some of which coalesced to form plaques or nodules also found on the masticatory mucosa (Figure 1D gingiva, Figure 1E hard palate).

In her medical history, she mentioned that her mother and sister have cutaneous papules, her son has similar oral lesions, and in her personal pathological history, she mentioned that she has a gynecological diagnosis of uterine fibroids, and that breast cancer has been excluded. In addition, she had undergone outpatient surgery for a lipoma of the lower extremity, a sebaceous cyst of the upper extremity, and multiple abdominal hernias.

A physical examination of the skin of the face and neck revealed dolichocephalic facies (Figure 2A–2C) and multiple papules on the dorsum and nasal tip (Figure 2D), small soft brown growths on the neck and lower eyelid (Figure 2E, 2F), and papules on the dorsum of the fingers (Figure 2G).

Laboratory studies were requested, including blood biometry, blood chemistry, and coagulation tests, and the results were reported to be within normal parameters. Subsequently, with the patient’s consent, an excisional biopsy of the enlarged volume located bilaterally in the jugal mucosa was performed under local anesthesia. The relevant histopathologic features revealed the presence of connective tissue hyperplasia surrounding a hamartomatous lesion (Figure 3A–3C).

The clinical and histological features described above raised suspicion of CS, and the genetic characteristics of the lesion were evaluated.

The patient was referred to the Oncogenetics Service of the Civil Hospital “Juan I Menchaca” of Guadalajara, where a study was performed using the MLPA (SALSA MLPA Probemix P225-PTEN®) assay to detect gains and/or losses in the PTEN gene in peripheral blood DNA. An abnormal genetic result was obtained, with loss of heterozygosity in exon 8. This result is interpreted as a heterozygous deletion of PTEN in the germline (Figure 4). This finding, together with the clinical characteristics, family history, and histopathological report, confirmed the diagnosis of CS.

Discussion

CS was first described in 1963 [3], and in 1972, Weary et al [9] described 5 cases: 1 male and 4 females, predominantly White race, with a mean age of 37.8 years (SD±5.16, min 32, max, 45), whose frequent clinical manifestations were located on the skin and mucosa. Current research indicates that CS exhibits a range of diverse and distinctive features on the skin and in the oral cavity [8]. Importantly, papules and papillomatous and verrucous lesions can be present on the gum and palate, as in our patient. These lesions can extend to the oropharynx and larynx, can include the scrotal tongue, and can grow to large dimensions. In addition, these lesions can manifest on the lip corner and the lateral borders of the tongue; in the gingiva, they can present a specific cobblestone pattern, which is an important sign to consider when examining the oral cavity [8,10].

Skin manifestations such as acrokeratosis or papillomatous and lichenoid lesions have been described [4,9]. Our patient had multiple papules, and her son and sisters also had papillomatous lesions on the skin and in the oral cavity. Lloyd and Weary posit that CS manifestations within the family lineage are distributed according to different degrees of syndromatic penetrance [4,9]. In 1983, Salem et al [11] conducted a review involving a series of cases with clinical criteria for the diagnosis of CS. In 2010, Farooq et al [12] established 3 different sets of criteria, classified as pathognomonic criteria, major criteria, and minor criteria. The clinical diagnosis of CS in our patient was confirmed through the fulfillment of 1 pathognomonic criterion (mucocutaneous lesions), 1 major criterion (macrocephaly), and 1 secondary criterion (uterine fibroids [myomas]). In addition, our patient reported that 2 direct relatives (mother and son) and a second-degree relative (sister) had papular lesions on the skin and oral mucosa (pathognomonic criteria), which could raise suspicions of CS according to Farooq et al [12], who described the following criteria for the clinical diagnosis of CS: (i) pathognomonic criteria, (ii) any 1 major criterion with or without minor criteria, (iii) 2 minor criteria, and (iv) a history of Bannayan-Riley-Ruvalcaba syndrome.

In 2013, Pilarski et al [13] published a set of clinical criteria for the diagnosis of PTEN hamartoma syndrome, divided into major and minor criteria. They recommend making an individual operational diagnosis when an individual presents with 3 or more major criteria, in which 1 is macrocephaly; or 2 major and 3 minor, with a family operational diagnosis in which an individual in the family meets 2 major criteria, 1 major and 2 minor criteria, or 3 minor criteria. Considering the recommendations made by Farooq et al [12] and Pilarski et al [13], our patient met the clinical criteria for diagnosis of CS.

Genetically, mutations in PTEN can lead to a wide range of phenotypic outcomes, resulting in disorders that may seem unrelated, such as cancer and autism spectrum disorders. Pathogenic germline mutations have been identified across 9 exons of the PTEN gene, including missense, nonsense, and splicing mutations, as well as deletions and intragenic insertions [2,14–17]. Notably, mutations in exons 5, 7, and 8 are frequently observed in the germline mutation spectrum and are associated with specific nonsense mutations, such as R130X, R233X, and R335X [14]. Exon 5 is particularly critical for germ-line mutations, as it contains the catalytic core motif [18,19]. Additionally, while data on PTEN promoter variants are limited, some pathogenic mutations in the promoter region have been shown to impact PTEN transcription and translation by altering the RNA secondary structure [20]. Specific pathogenic intronic variants in PTEN can lead to exon skipping, alternative splicing, or activation of cryptic splice sites [21]. Large deletions and duplications involving PTEN are relatively rare but can occur throughout the coding sequence [14,17]. To support clinically relevant and evidence-based classification of PTEN mutations in the germline, the Clinical Genome Resource (ClinGen) established the PTEN Variant Cure Expert Panel to guide these efforts [22].

PTEN mutations are associated with the presence of macrocephaly and autism spectrum disorders, and performing genetic studies to detect PTEN mutations is recommended, even if these patients do not present clinical characteristics [23].

Other cases have been diagnosed using immunomarkers such as Bcl-2. S-100 and ki-67 [24].

Despite meeting the clinical criteria for a diagnosis of CS, our case required further analysis using MLPA. This analysis not only confirmed the CS diagnosis, but also allowed for a risk assessment for cancer development to be carried out. It is important to emphasize that a positive MLPA result helps patients, and their families also benefit from the early detection of diseases related to this syndrome. Moreover, a confirmed MLPA result offers a comprehensive understanding of the patient’s overall health risks, enabling more personalized clinical management [25].

Surveillance guidelines are tailored to the specific tumors associated with CS, including breast carcinoma, non-medullary thyroid carcinoma, endometrial adenocarcinoma, renal cell carcinoma, and, potentially, melanoma. Both men and women should undergo comprehensive annual physical exams beginning at age 18, or 5 years before the youngest age at which a family member was diagnosed with any of these cancers. These exams should specifically focus on changes in the skin and thyroid region. Women should begin annual clinical breast exams and training in breast self-examination at around 25 years old. Mammographic screening should start at age 30 or 5 years prior to the earliest age at which breast cancer was diagnosed in the family. These recommendations were established by the National Comprehensive Cancer Network (NCCN), which also advises annual endometrial surveillance, including biopsies, beginning at age 35 or 5 years prior to the youngest age of endometrial cancer diagnosis within the family. Additionally, incorporating annual urine tests for blood into the routine physical exam could be beneficial [26].

The recommendations given by the NCCN were explained to the patient, including studies of the early detection of cancer related to CS; unfortunately, the patient did not agree to these recommendations, and was therefore advised to keep a close eye on the situation and to undergo a medical check-up at least twice a year for detection of any problems.

Conclusions

We present a case report with clinical and familial features highly suspicious of PTEN in which, fortunately, malignant alterations were ruled out. However, the patient’s presentation was clinically consistent with CS, and genetic testing confirmed the diagnosis, so it is of utmost importance that health personnel (physicians, dentists, and psychologists) are trained to recognize these clinical characteristics to establish a proper diagnosis supported by genetic evaluation. This is especially true for patients with macrocephaly and autism spectrum disorders who do not have clinical manifestations of CS. In addition to alerting the patient to the development of potential malignant disorders associated with this type of neoplasm, the early detection of CS enables treatment and appropriate follow-up to be conducted in a timely manner.