Cystic basal cell carcinoma_1212 Derm Clinic 2
A white man, aged 60 years, presented with a lesion on the left nasal sidewall. The growth had developed about two years earlier and had not grown since then. There was no pain or tenderness associated with the lesion.
The man’s medical history was negative for skin cancer, and family history was noncontributory. Physical exam revealed a 5-mm, translucent, fluid-filled papule on the left nasal sidewall with overlying telangiectasias. The rest of the exam was notable for erythematous scaling macules and papules in sun-distributed areas, including the face, dorsal forearms, and hands. A biopsy was obtained.
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The lesion was clinically suggestive of a benign apocrine hidrocystoma; however, the overlying telangiectasias and background actinic damage raised suspicion for possible malignancy. Biopsy showed histopathology notable for dermal islands of basaloid cells with peripheral palisading and stromal retraction. A diagnosis of cystic basal cell carcinoma (BCC) was made.
BCC is the most common cancer in the United States.1 There has been a troubling rise in the incidence of BCC over the past three decades.2 The greatest risk factor for the development of BCC is skin phenotype, with a five- to 10-fold increased risk in lightly pigmented individuals compared with darkly pigmented individuals. Other established risk factors include male gender, radiation therapy, family history of BCC, and immunosuppression.
The pathogenesis of BCC appears to depend on both UV exposure and genetics. Two important and distinct pathways in the development of BCC are (1) UVB irradiation inducing DNA mutations in the p53 tumor suppressor gene and (2) mutations in the Hedgehog signaling pathway.3 With regard to the latter, the most common mutation is inactivation of the Patched1 gene followed by SMO mutations, which are associated with 10%-20% of sporadic BCCs.2
Several genetic conditions have been associated with increased risk of BCC. Nevoid BCC syndrome (also referred to as Gorlin syndrome) is an autosomal dominant disorder caued by mutation in the PTCH gene. In addition to numerous BCCs, this condition is characterized by palmar and plantar pits, odontogenic keratocyts of the jaw, and calcification of the falx cerebri. There is an increased risk of medulloblastoma in early childhood, so annual MRI is recommended until the patient reaches age 5 years.
Bazex syndrome is an X-linked dominant disease with follicular atrophoderma (i.e., circumscribed areas on dorsal hands and feet), localized hypohidrosis, hypertrichosis, and epidermoid cysts. Multiple BCCs, typically on the face, develop by the second decade.
Finally, Rombo syndrome is also characterized by an increased risk of BCCs; however, in contrast to Bazex syndrome, Rombo syndrome is notable for vermicular atrophoderma (i.e., worm-eaten appearance of cheeks) and hypotrichosis. All of these genetic syndromes are rare and should only be considered when a patient presents with multiple BCCs of early onset.2
There are many clinical variants of BCC. Approximately 60% of BCC cases are the nodular subtype, classically described as a pearly nodule with characteristically rolled borders and overlying telangiectasias. The most common location for nodular BCCs is the head and neck, especially the nose.
Another common subtype of BCC is the superficial variant, which commonly presents as erythematous scaly lesions on the trunk or distal extremities. It is not uncommon to have multiple superficial BCC lesions simultaneously.
In darkly pigmented individuals, the most common variant is the pigmented BCC, which presents as waxy papules with varying amounts of dark globular pigment. Last, morpheaform BCC often has a subtle presentation but a more aggressive course. This variant presents as a white sclerotic plaque and is often mistaken by patients and clinicians as scar tissue.1
Histologic variants include infiltrative and micronodular BCC. Fibroepithelioma of Pinkus is a rare clinical and histologic variant presenting as a flesh-colored, pedunculated papule on the trunk. The patient in this case represents the cystic variant of BCC, which presents as a translucent blue-gray nodule.
Any clinical variant of BCC left untreated will become increasingly large and locally destructive. When ulceration develops, the BCC is often referred to as a rodent ulcer or Jacobi ulcer.1
The differential diagnosis depends on the clinical variant. Nodular BCC can be confused with sebaceous hyperplasia, as both have waxy surfaces and are commonly found on the face. Sebaceous hyperplasia has a yellowish hue and often features a central depression.
Superficial BCC has many clinical mimics because of its nonspecific appearance. Superficial BCC can also be difficult to distinguish from eczema, squamous cell carcinoma in situ, and benign lichenoid keratoses.
The differential diagnosis of pigmented BCC can include Spitz nevus, compound nevus, and melanoma. As stated above, morpheaform BCC can appear indistinguishable from a scar.
Fibroepithelioma of Pinkus bears striking similarity to acrochordons (i.e., skin tags). In most variants, with the exceptions of fibroepithelioma of Pinkus and superficial BCC, close examination can reveal the characteristic “rolled border” appearance of BCC.
History is also helpful: Even when lesions look clinically benign, a history of growing lesion or a lesion that bleeds with minimal or no history of trauma should raise suspicion for malignancy.
Although a diagnosis of BCC can be made clinically, it must be confirmed by biopsy. Despite the numerous clinical presentations, the majority of BCCs have very similar histology. The classic histologic findings include islands of small, dark-staining basaloid cells. Cells may line up as a “picket fence” at the periphery of the islands. There is often retraction of the basaloid islands from the surrounding stroma.
Special stains, such as metachromatic toluidine blue, can assist in the diagnosis by highlighting the stroma. High-risk histologic types include infiltrative, morpheaform, and micronodular variants. These types have a higher incidence of locally invasive behavior with a higher risk of recurrence.
Treatment depends on several factors, including histologic type, patient preference, and size and location of the tumor. The preferred methods of treatment for most BCCs include curettage or local excision with 4-mm margins. Exceptions to these methods include superficial BCC, which can be treated with topical imiquimod (Aldara) 5% cream applied five nights a week for six weeks. The cure rate may be as high as 80% with this modality, but patient compliance is a significant issue.
BCC treatment should be managed by a dermatologist, as residual malignancy after therapy may be difficult to detect. High-risk histologic types, recurrent BCCs, or lesions on cosmetically sensitive areas (i.e., the nose and periorbital and perioral regions) should be referred for Mohs microscopic surgery or to a plastic surgeon. The cure rate for primary and recurrent BCCs by Mohs surgery has the highest rate of clearance and lowest rate of recurrence compared with all other treatment modalities.
The patient in this case opted for curettage. To date, no evidence of recurrence has been noted.
Audrey Chan, MD, is a second-year resident in the Department of Dermatology; Shazia Ali, MD, is a fourth-year medical student; and Yi Deng, MD, is a second-year resident in the Department of Anesthesiology, all at Baylor College of Medicine in Houston.
- James WD, Berger TB, Elston DM. Andrews’ Diseases of the Skin: Clinical Dermatology. 11th ed. Philadelphia, Pa,: Saunders-Elsevier; 2011:633-639.
- Bolognia JL, Jorizzo JL, Rapini RP, eds. Dermatology. 3rd ed. St. Louis, Mo.: Elsevier-Mosby; 2012:1641-1658.
- Wong CS, Strange RC, Lear JT. Basal cell carcinoma. BMJ. 2003;327:794-798.