Melanoma arising from an epidermal inclusion cyst

Is it Necessary to Send Clinically Diagnosed Benign Skin and Subcutaneous Lesions Excised Under Local Anesthesia for Routine Histopathological Examination?

Background

The common benign surgical lesions of skin and subcutaneous tissues like lipoma and sebaceous cysts are diagnosed clinically and treated by surgical excision under local anesthesia. The occurrence of malignancy in these lesions is extremely low, and routine histopathological examination (HPE) adds to increased costs and workload on pathologists. This study was undertaken to estimate the clinical concordance and the frequency of malignancy in these lesions.

Methods

A total of 1,815 HPE reports of clinically benign skin and subcutaneous lesions excised under local anesthesia from January 2014 to December 2018 were studied.

Results

Lipoma (31.3%) and sebaceous cyst (29.9%) were the common clinical diagnosis in our study. The clinical accuracy in the diagnosis of lipoma was 88.6%, and for sebaceous cyst, it was 72.7%. There were six reports of malignancy in our study from the clinically diagnosed benign skin and subcutaneous lesions (0.33%). None of the cases of lipoma and the sebaceous cyst had a malignancy in the final histopathology report. The frequency of malignancy in the rest of the lesions is 0.85% (six out of 699 cases); (p-value: 0.003).

Discussion

In the absence of red flag signs, lesions like lipoma, sebaceous cyst, corn, and callus can be discarded without an HPE. We advocate routine HPE of other solid lesions, cystic lesions with solid areas, and pigmented or ulcerated lesions, as the clinical concordance is low and there is a significant occurrence of malignancy in these lesions.

Skin malignancy initially misdiagnosed as a benign epidermal cyst

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.

Is Routine Pathologic Evaluation of Sebaceous Cysts Necessary?: A 15-Year Retrospective Review of a Single Institution

A question arose in our practice of whether all cysts considered sebaceous should be sent for pathologic evaluation. To address this controversial topic, we performed a retrospective study of our single institution's histopathology database. A natural language search of the CoPath database across the institution was undertaken using the diagnosis of sebaceous cyst, epidermal cyst, epidermoid cyst, epithelial cyst, infundibular cyst, pilar cyst, trichilemmal cyst, and steatocystoma. A surgical pathologic review of all specimens with one of these preexcision diagnoses was included in the 15-year retrospective study of 1998 to 2013. All slides were confirmed to have undergone histopathologic review, and the preexcision diagnoses were compared with the postexcision diagnoses. Chart review was undertaken in instances of a diagnosis of malignancy. A total of 13,746 samples were identified. Forty-eight specimens had histopathologic diagnosis of malignancy, for an incidence of 0.3% and with the most common malignancy being squamous cell carcinoma. Chart review showed that for all cases, the surgeons reported uncertainty with regard to the diagnosis because of history or physical characteristics, or both. In addition, a comprehensive literature review showed results consistent with our data and illustrated 19 cases during the past 10 years in which most of the findings were squamous cell carcinoma. We propose the recommendation that routine pathologic evaluation of sebaceous cysts is necessary only when clinical suspicion exists.

Post Surgical Giant Epidermal Inclusion Cyst of the Lid and Orbit- A Rare Case

Epidermoid cyst within the lid and orbit is extremely rare. Epidermoid tumours are inclusion of ectodermal elements in the site not normally containing these structures. It is of two types; primary type related to implantation of ectoderm at the time of closure of the neural groove and secondary type caused by post traumatic inclusion of the surface epithelium. A 45-year-old male had complaint of swelling on the right upper lid and orbital region. It first appeared two years back. It was painless progressively increased in size and shape. There was difficulty in opening of eye lid due to large swelling, feeling of heaviness in the right upper lid and occasional headache. There was history of right eye ocular infection following vegetative matter injury three years back. Evisceration of right eye was done for aforementioned reason. USG report shows cystic encapsulated mass with calcification foci in right upper lid-orbital region with fat component. MRI right orbit shows fairly large hyperintense cystic lesion seen involving right orbit with posterior extension up to optic canal. No intracranial extension. FNAC confirmed epidermal inclusion cyst. We did upper lid reconstruction with removal of mass. We have successfully removed the mass without any complication and with one year follow-up there is no recurrence.