After having read the introductory article on basal cell carcinoma (BCC), you are very much aware that BCC is the most common type of skin cancer and the most common malignancy in humans. If you haven’t read that article, then you’ve just learned a new fact! Now that you know this important fact, why not educate yourself on the variety of ways that the most common human cancer can present on the body?
THE “FLAVORS”
Luckily, the different types of basal cell carcinoma do not come in as high a number as the original 31 ice cream flavors of Baskin Robbins! In fact, the clinically recognizable “flavors” of basal cell carcinoma do not even (thankfully!) reach double digits. However, there is some controversy over how many distinct variations truly exist. Some resources list four different types, while others prefer five types, and still others outline six types.
At this point, you may be scratching your head and asking yourself why it is important to identify the specific type of basal cell carcinoma. The reason is because recognition dictates treatment. In other words, when a dermatologist diagnoses a more aggressive BCC, more aggressive therapy is often necessary.
The general consensus amongst the experts js that there are four distinguishable types of basal cell carcinoma—nodular, pigmented, superficial, and morpheaform (a.k.a sclerosing). Although not readily accepted as clinically distinct types of BCC, this section will also outline two others—cystic and micronodular—for the sake of completion, even though some experts consider the cystic and micronodular variants to be subtypes of nodular BCC.
1. Nodular: This is the most common type of BCC in the general population. It occurs on chronically sun-exposed areas, especially the head, neck, and upper back. It typically appears as a translucent, shiny, skin-colored papule or pinkish nodule. Its appearance depends on how long it has been growing – with time, a papule evolves into a nodule, which is deeper). Telangectasias (small blood vessels that run across or radiate over the lesion) and a rolled border (lesion edges that are more elevated than the surrounding skin) are often appreciated. It may spontaneously bleed, then heal, and cyclically exhibit this pattern over time. Historically, large lesions with central necrosis (dead skin in the middle of the lesion) are known as rodent ulcers.
2. Pigmented: This is the most common type of BCC in individuals with darker skin. It exhibits the same characteristics as nodular BCC but differs due to increased melanin deposition (which is what makes it pigmented). Because pigmented BCC shares many traits with nodular BCC, some experts argue that it is actually a subtype of nodular BCC, while other experts say pigmented BCC deserves its own distinction. Lesions are typically brown, blue, or grayish in color, and the hyperpigmentation is often described as dark droplets within the lesion.
3. Superficial: This is the most common type of BCC found on the trunk. It typically appears as irregular, scaly patches pink to red-brown in color with central clearing. These lesions grow very slowly and rarely become invasive. Despite its patchy irregularity, the lesion overall is often well-demarcated (which means that there is a clear and distinct border between where the lesion ends and normal skin begins). Erosion is less common when compared to other types of BCC. Interestingly, numerous superfical BCCs diagnosed in an individual might indicate arsenic exposure.
4. Morpheaform (a.k.a. Sclerosing): This is an aggressive type of BCC. These lesions can occur anywhere but are usually found in the mid-facial area. They can appear as waxy, sclerotic plaques or papules, or can resemble small lesions of morphea—areas of hardened skin. In addition, lesions can be ivory-white in color, resembling a scar. As such, these lesions are often mistaken for simple scar tissue. That being said, morpheaform BCC should be suspected when “scar tissue” appears in the absence of trauma or previous surgical excision. The borders are often ill-defined and features such as ulceration, bleeding, and crusting are uncommon. Given its aggressive nature, recurrence after treatment is common. If atypical-appearing tissue arises in an area of excision (where normal scar tissue should develop), recurrence should be suspected.
5. Cystic: This may or may not be regarded as a clinically distinct variant, as some consider it a subtype of nodular BCC. It mostly appears as translucent, blue-gray nodules. These lesions are soft to the touch and contain jelly-like contents. They have the potential to mimic benign cystic lesions, so clinical suspicion is key.
6. Micronodular: Again, this may or may not be regarded as a clinically distinct variant, as some consider it a subtype of nodular BCC. In regards to similarity, these lesions display the typical distribution pattern of basal cell carcinoma, meaning this type of BCC is found on the areas of the body this cancer often affects (i.e. head and neck). Otherwise, lesions appear yellow-white when stretched and feel firm to the touch. It does not ulcerate and, although it appears to have a well-defined border, it is not a benign lesion. In reality, these lesions are aggressive and can be quite deep.
REFERENCES:
Carucci JA and Leffell DJ. Basal Cell Carcinoma. In Wolff K, Goldsmith LA, Katz SI, et al: Fitzpatrick’s Dermatology in General Medicine, 7th ed. New York: McGraw-Hill Companies. 2003.
Habif TP, Campbell JL, Quitadamo MJ, and Zug KA. Basal Cell Carcinoma. In Fathman EM and Giesel EB: Skin Disease: Diagnosis and Treatment. St. Louis: Mosby. 2001.
Ramsey ML and Sewell LD. Basal Cell Carcinoma. [document on the Internet]. WebMD: eMedicine; 2009. [updated 2009 September 11; cited 2009 December 15]. Available from: http://emedicine.medscape.com/article/1100003-overview
DermNet NZ. Basal Cell Carcinoma. [document on the Internet]. New Zealand Dermatological Society Incorporated; 2009. [updated 2009 June 15; cited 2009 December 15]. Available from: http://dermnetnz.org/lesions/basal-cell-carcinoma.html