That’s So Based of You Cancer

Based. The base. The basal layer. Basal cell carcinoma (BCC). BCC plays the bass. The base is played by Steve Harris. Steve Harris is BCC. I play the bass so I am either Steve Harris or BCC. Will I ever grow up? Probably not. Alas, BCC is the word(s) of the day. 

I posted about cutaneous squamous cell carcinoma (cSCC) a bit ago and BCC is his less athletic sibling. Thinking back, cSCC arises from mutations in the squamous epithelium that lines our organs and forms part of our skin. Basal cell on the other hand arises from the base layer of skin and thought to start from the stem cells that differentiate into hair follicles and sweat glands. 

These stem cells usually get damaged by UV radiation (looking indirectly at you sun) but can also be damaged by smoking and high levels of toxic chemicals like arsenic. It is mostly liked to sun however, but does become more likely in those with a compromised immune system that doesn’t identify and attack the mutant cells before they proliferate. Compared to cSCC, BCC is not as common, given that we have more squamous epithelial cells, so cSCC is more commonly associated with immunosuppressive therapy or conditions. Think organ transplants, long term steroid use, biologic use, uncontrolled HIV/AIDS, among other conditions. It is also hypothesized that BCC is related more to the intensity of individual sun exposures as opposed to cSCC being associated with cumulative exposure.

The other interesting cause is basal cell nevus syndrome, which effects at least one tumor suppression gene related to the development of BCC. It is so common to develop BCC with this condition that only <10% of people with this condition don’t develop BCCs. Those with the condition usually develop BCC under 20 years of age which is extremely rare otherwise. 

To say death from BCC is rare is an understatement but it can cause serious damage to local tissues and impinge on vital structures. The death rate from the NIH is 0.12 per 100,000 age adjusted years. The damaged skin may also place patients at higher risk of infection, especially in those with the immunodeficiency factors listen above. 

While BCC is generally thought of as the slow-mo skin cancer, certain subtypes are more aggressive than others. A very good episode of The Grenzzone (ep 16) does an excellent job of explaining the differences in a way even people like I can understand. These include nodular, superficial, invasive, morpheaform, pigmented, micronodular, basosquamous, desmoplastic, infundibulocystic, and others. Morpheaform, basosquamous, and sclerosing being more aggressive and having a higher chance of recurrence. 

Regardless of the aggressiveness or lack thereof, BCC can become large and disfiguring, as mentioned above. About 1% of treated BCC are over 5cm at their widest. The largest I could find was 25cm but I am sure that is not the record. I swear my doc treated one at least 26cm per the path report, but I could be crazy. It is always grotesquely fun to look for the "biggest" something, in this case, the biggest is also the most likely to metastasize. You may ask now, "John, why the heck should I care?" If you are a nurse I will say, as I have said in some previous post, that you get to look at more of the patient's skin than the doc does. We should be able to notice changes, spots that bleed with little provocation, and the like. 

Speaking of what to look for, BCC can run the gamut. With the most common appearance as a pearly lesion with rolled edges and if you look closely and say telangiectasia 3 times in front of a mirror in a dark bathroom, they may just be there. Actually, just look close like, no need for incantations. Superficial BCC can look a lot like a rash, morpheaform like a scar, sclerosing like an ulcer, and pigmented like a melanoma. So, everything. Key takeaways (general rules but yes, I know there are exceptions) though are most common on the head and neck, bleed with little trauma, persist for months, and usually present with a pearly lesion with rolled borders and teeny tiny, itty bitty, mini fun sized blood vessels. 

I won't talk about treatment much. The standards are Mohs and excision but ED&C, cryosurgery, topical chemotherapy, intralesional chemotherapy, radiation, phototherapy, systemic chemotherapy, and immune therapy all have their place. I am super interested in PO, topical, or intralesional treatments that save patients from cutting if we can help it. I wrote a bit about itraconazole previously and pembrolizumab just got unresectable BCC added to its indications. Then there are the hedgehog inhibitors. Anyways, super duper fascinating. I have a lot of sympathy for patients, not that I have had any skin surgeries, but I take forever to heal so I can image getting these cut out is worse (the plural of anecdote is anecdotes so I think this is true). 

Thanks for reading, check out the podcast, Instagram @occasionally_preposterous or Twitter @preposterjohn

Love y'all, bye bye.

References 

Basal cell carcinoma from StatPearls at the NIH: National Library of Medicine

Clinical and Dermoscopic Factors for the Identification of Aggressive Histologic Subtypes of Basal Cell Carcinoma by Pampena et al., in Frontiers in Oncology February 2021

Neglected cutaneous skin malignancy: A patient with concurrent giant basal cell carcinoma and melanoma from Skin Health and Disease 2021 by Sun & Tan (no I did not make that up)

Patterns and timing of sunlight exposure and risk of basal cell and squamous cell carcinomas of the skin-a case-controlled study from BMC Cancer 2012 by Iannacone et al.

Picture of Histological examination of a morpheaform BCC from Wikipedia 

Wide variety of case reports from PubMed and the googles on "largest BCC"