Skin cancer, which often occurs as a result of skin exposure to ultraviolet light radiation, usually presents with characteristic abnormal features, such as ulcerative lesions, irregular morphology, bleeding, and excessive growth. Therefore, skin cancer rarely resembles a benign tumor on visual inspection. Nonetheless, squamous cell carcinoma and basal cell carcinoma with nodular or polypoid features can have a similar appearance to that of benign tumors, meaning that they are sometimes misdiagnosed as benign. As benign and malignant tumors have some overlapping features, clinicians sometimes use additional imaging techniques such as ultrasonography to improve the accuracy of the diagnosis because even a malignant tumor that externally resembles a benign tumor generally has internal morphological features characteristic of malignancy, such as invasion and irregular borders. However, these imaging tools also have limitations, and punch or excisional biopsy can be needed if malignancy cannot be completely ruled out. Herein, we report a case of skin malignancy initially misdiagnosed as a benign epidermal cyst based on external visual inspection and ultrasonography.
Skin malignancy usually occurs as a result of chronic damage from sunlight [
An 81-year-old man with three masses in his left periauricular region was referred to our department. The patient reported that he originally had a nevus in the region and underwent a nevus removal procedure at a dermatology clinic 2 years ago.
There were two posterior masses (upper, 2.6×2.0 cm; lower, 1.7×1.4 cm) and one anterior mass. The two posterior masses were erythematous dome-shaped nodules connected to each other. Meanwhile, the anterior mass (1.2×1.2 cm) was smaller than the other two masses and showed a small ulcerative opening covered by a crust (
An excisional biopsy was performed under local anesthesia. A lazy S-shaped incision was made to expose all the three masses. Intraoperatively, we found that the three masses were composed of lumps of necrotic tissue, instead of showing the expected characteristics of a cystic mass. A histopathological examination showed atypical keratinocytes with hyperchromatic nuclei growing into the dermis suggesting that the anterior mass could be SCC (
Over a 2-year period, the patient and his guardian were informed of conservative treatment methods such as avoiding additional ultraviolet exposure and keeping the affected area clean. Although the discharge persisted for 2 years, we observed no findings that suggested malignant growth, such as increased lesion size, additional ulceration, or a polypoid lesion.
The epidemiological characteristics of skin malignancies, especially BCC and SCC, have been thoroughly analyzed. According to previous studies, a leading risk factor of skin malignancy is exposure to ultraviolet light radiation [
Several studies have also explored associations between benign and malignant skin tumors. Veenstra et al. [
US findings are very helpful in the diagnosis of soft tissue tumors. On US, an unruptured epidermal cyst presents as a well-circumscribed mass, with a heterogeneously and mildly echogenic appearance. A ruptured epidermal cyst is usually seen as an irregularly marginated hypoechoic lesion, and an infected epidermal cyst shows increased blood flow in and at the periphery of the mass on Doppler US [
This case report has some limitations. First, no further pathological findings were obtained, as an additional wide local excision was not performed because the patient and his guardian refused. Had a wide local excision been performed, we might have obtained additional information about how the tumor developed in this case. Second, we could not precisely determine the dermatological procedure performed 2 years before the patient underwent the present excision, so we were not able to explore its possible association with his skin cancer.
In the present case, it was unclear whether a benign tumor developed first and then turned malignant, or a malignant tumor developed first and simply showed the morphology of a benign tumor. However, physicians must suspect skin malignancy in the presence of any indication that suggests a malignant lesion, even if a lesion presents features similar to those of a benign tumor on visual inspection and has radiological findings implying benignity.
No potential conflict of interest relevant to this article was reported.
The study was approved by the Institutional Review Board of Hallym Sacred Heart Hospital (IRB No. 2019-10-001) and performed in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained.
The patient provided written informed consent for the publication and the use of his images.
An 81-year-old man with three masses in his left periauricular region. The two posterior masses (upper mass, 2.6×2.0 cm; lower mass, 1.7×1.4 cm), and the anterior mass (1.2×1.2 cm) are shown.
Visualization of the masses on ultrasonography. Ultrasonography showed (A) the anterior mass and (B) the posterior masses, which were connected with each other.
Histopathological images showing squamous cell carcinoma and basal cell carcinoma. (A) Atypical keratinocytes with hyperchromatic nuclei (arrow, H&E, ×200) and (B) basaloid cell proliferation with peripheral palisades and a cleft between the tumor and stroma (arrows, H&E, ×100).
Postoperative photograph 3 weeks after surgery. Two small wounds are shown where the masses were located.
Postoperative computed tomography scan showing the residual tumor. Several areas of skin thickening with enhancement in the left periauricular area (arrows) confirmed the presence of residual tumor tissue.