Fibroepithelioma of Pinkus (FeP), or Pinkus tumor, is a rare tumor with a presentation similar to benign neoplasms such as acrochordons and seborrheic keratoses. Classically, FeP presents as a nontender, solitary, flesh-colored, firm, dome-shaped papule or plaque with a predilection for the lumbosacral region rather than sun-exposed areas. This tumor typically develops in fair-skinned older adults, more often in females.1
The association between cutaneous lesions and internal malignancies is well known to include dermatoses such as erythema repens in patients with lung cancer, or tripe palms and acanthosis nigricans in patients with gastrointestinal malignancy. Outside of paraneoplastic presentations, many syndromes have unique constellations of clinical findings that require the clinician to investigate for internal malignancy. Cancer-associated genodermatoses such as Birt-Hogg-Dubé, neurofibromatosis, and Cowden syndrome have key findings to alert the provider of potential internal malignancies.2 Given the rarity and relative novelty of FeP, few studies have been performed that evaluate for an association with internal malignancies.
There potentially is a common pathophysiologic mechanism between FeP and other benign and malignant tumors. Some have noted a possible common embryonic origin, such as Merkel cells, and even a common gene mutation involving tumor protein p53 or PTCH1 gene.3,4 Carcinoembryonic antigen is a glycoprotein often found in association with gastrointestinal tract tumors and also is elevated in some cases of FeP.5 A single-center retrospective study performed by Longo et al3 demonstrated an association between FeP and gastrointestinal malignancy by calculating a percentage of those with FeP who also had gastrointestinal tract tumors. Moreover, they noted that FeP preceded gastrointestinal tract tumors by up to 1 to 2 years. Using the results of this study, they suggested that a similar pathogenesis underlies the association between FeP and gastrointestinal malignancy, but a shared pathogenesis has not yet been elucidated.3
With a transition to preventive medicine and age-adjusted malignancy screening in the US medical community, the findings of FeP as a marker of gastrointestinal tract tumors could alter current recommendations of routine skin examinations and colorectal cancer screening. This study investigates the association between FeP and internal malignancy, especially gastrointestinal tract tumors.
Methods
Patient Selection—A single-center, retrospective, case-control study was designed to investigate an association between FeP and internal malignancy. The study protocol was approved by the institutional review board of the Naval Medical Center San Diego, California, in compliance with all applicable federal regulations governing the protection of human subjects. A medical record review was initiated using the Department of Defense (DoD) electronic health record to identify patients with a history of FeP. The query used a natural language search for patients who had received a histopathology report that included Fibroepithelioma of Pinkus, Pinkus, or Pinkus tumor within the diagnosis or comment section for pathology specimens processed at our institution (Naval Medical Center San Diego). A total of 45 patients evaluated at Naval Medical Center San Diego had biopsy specimens that met inclusion criteria. Only 42 electronic medical records were available to review between January 1, 2003, and March 1, 2020. Three patients were excluded from the study for absent or incomplete medical records.
Study Procedures—Data extracted by researchers were analyzed for statistical significance. All available data in current electronic health records prior to the FeP diagnosis until March 1, 2020, was reviewed for other documented malignancy or colonoscopy data. Data extracted included age, sex, date of diagnosis of FeP, location of FeP, social history, and medical and surgical history to identify prior malignancy. Colorectal cancer screening results were drawn from original reports, gastrointestinal clinic notes, biopsy results, and/or primary care provider documentation of colonoscopy results. If the exact date of internal tumor diagnosis could not be determined but the year was known, the value “July, year” was utilized as the diagnosis date.
Statistical Analysis—Data were reviewed for validity, and the Shapiro-Wilk test was used to test for normality. Graphical visualization assisted in reviewing the distribution of the data in relation to the internal tumors. The Fisher exact test was performed to test for associations, while continuous variables were assessed using the Student t test or the nonparametric Mann-Whitney U test. Analysis was conducted with StataCorp. 2017 Stata Statistical Software: Release 15 (StataCorp LLC). Significance was set at P<.05.