Cutaneous Basal Cell Carcinoma In Situ: A Case Series

Basal cell carcinoma, squamous cell carcinoma, and melanoma are three types of skin cancers. Skin cancers present as either non-invasive malignancies or invasive neoplasms. The non-invasive malignancies are referred to as carcinoma in situ; they only have cancer cells that are restricted to the epidermis and are not present as single tumor cells or independent nests of malignant cells in the underlying dermis. In contrast, invasive neoplasms demonstrate individual malignant cells or aggregates of tumor cells or both that are found in the dermis; in addition, cancer cells may also be located in the overlying epidermis. The features of three men with basal cell carcinoma in situ of the skin are described in this case series. Each of their tumors morphologically appeared as a red, scaly or non-scaly, and superficial plaque on the abdomen or the back; the neoplasm was successfully treated without recurrence by either surgical excision or by topical 5% imiquimod cream. Cutaneous basal cell carcinoma in situ has characteristic morphologic and pathologic findings. Clinically, cancer most commonly appears as a thin, smooth-surfaced or scaly, and as an erythematous plaque on the trunk. Microscopic examination shows multiple sites of basaloid tumor cells that either nearly filled the epidermis and/or replaced the lower layers of the epidermis; the aggregates of tumor cells may expand the epidermis and display slight extension into the papillary dermis. However, there is no non-contiguous invasion of the tumor cells from the overlying epidermis into the underlying dermis. Palisading of the peripheral tumor cells is noted; in addition, focally, retraction of the dermal stroma from the tumor is also frequently present. Lymphocytic inflammation may also be present in the upper dermis. Similar to the reported patients, since basal cell carcinoma in situ of the skin is only localized to the epidermis, several therapeutic modalities are available to effectively treat the cancer. However, if the basal cell carcinoma in situ represents the superficial portion of a basal cell carcinoma of mixed histology, tumor persistence or recurrence may occur if a more conservative approach to treatment is utilized that does not adequately treat the unsuspected and more aggressive pathologic subtype of basal cell carcinoma in the underlying dermis. In summary, basal cell carcinoma in situ of the skin has a unique clinicopathologic correlation of morphology, histology, tumor biology, and response to treatment; indeed, tumors that were previously classified as superficial basal cell carcinoma are more appropriately designated as cutaneous basal cell carcinoma in situ.