Diagnosis: Pigmented basal cell carcinoma
Pigmented basal cell carcinoma (PBCC) usually presents as a hyperpigmented, crusted, ulcerative nodule that grows very slowly on sun-exposed skin (Figure). All forms of cutaneous malignancy are less common in individuals with higher Fitzpatrick skin types (ie, IV-VI). This is attributed to the inherent photoprotection of melanin and melanosomal dispersion, creating a barrier for UV damage. Potential causative agents in the pathogenesis of cutaneous malignancy in American Blacks include, but are not limited to, sunlight, albinism, burn scars, x-rays, chronic inflammation, and chronic discoid lupus erythematosus.1 Despite the inherent photoprotection of melanin and melanosomal dispersion in darker skin, more than half of all BCCs of the skin in American Blacks occur in areas with greater sun exposure, such as the head and neck.2 However, sunlight is considered to be less significant in the formation of BCC in American Blacks than in American Whites. Other factors may be involved, as a relatively high proportion of BCCs on American Blacks are found on nonexposed areas of the body, including the trunk, groin, upper and lower extremities, back, prepuce, and nipple.2 The reasons why this occur are not entirely well described.
Maloney et al3 studied 1039 BCC lesions and found that 70 contained pigment, comprising approximately 6% of all BCC variants. Cases reported in the literature have been mostly from those of darker complexioned persons, such as Latin Americans, Hispanics, or Asians.
Only 1.8% of BCCs occur in American Blacks.4 Also, BCCs are 19 times more likely to occur in Whites than in Blacks.4 Data is limited for this racial group due to the combination of low incidence and lack of reporting of nonmelanoma skin cancer to tumor registries,1 making accurate determination of incidence and mortality for BCC difficult in American Blacks. BCC comprises 12% to 35% of skin cancers in American Blacks and 2% to 8% in African Blacks.5
Histologic features of PBCC include nests of pigmented basaloid tumor cells with large melanosome complexes and interspersed granules of melanin, surrounded by melanophages. The melanophages have difficulty transferring melanin to basaloid tumor cells, leading to melanin-laden melanophages and melanocytes that create the hyperpigmentation visualized on gross examination. A basal cell epithelium cell has poorly developed monofilaments in its cytoplasm, blocking the transfer of melanin and melanosomes from melanophages. The melanocytes themselves are of normal morphology and are in various stages of development.3,6,7
Differential diagnosis of PBCC includes pigmented seborrheic keratosis, cutaneous sarcoidosis, granuloma faciale (GF), granuloma annulare, and actinic granuloma (Table). Dermoscopy is vital in distinguishing PBCC from melanoma and the aforementioned entities. On dermoscopy, PBCC may demonstrate large gray-blue ovoid nests, multiple gray-blue globules, maple leaf-like areas, spoke wheel areas, ulceration, or arborizing “treelike” telangiectasia.8 PBCCs often have the features of nodular BCC but with the addition of brown or black pigmentation.9,10
Cutaneous sarcoidosis is a protean eruption, but it often manifests as reddish purple to violaceous or brown, shiny, indurated plaques on the face, especially on the nasal alae, cheeks, lips, and ears. GF usually presents with one or more reddish, brown, or violaceous pruritic plaques on the forehead (38%), cheeks (30%), nose (27.5%), or eyelid (10.5%).11 Multiple GF plaque and nodular lesions were present in a significant proportion of cases (38%), but ulceration is rare.11 Granuloma annulare is characterized by a raised annular distribution of papules, most frequently on the dorsal surfaces of the hands and feet, fingers, and extensor aspects of the arms and legs.12 Actinic granuloma presents as an annular plaque defined by smooth, slightly raised, pearly borders with a center that may display slight atrophy, frequently occurring on the face.13
The standard for treatment of PBCC is surgical excision or Mohs surgery. One study found that the mean surgical margin taken was smaller in the PBCC than the nonpigmented BCC group (3.89 vs 5.85 mm; P<.05).14 This could be due to the fact that PBCC has a more sharply demarcated tumor border than nonpigmented BCC and the conspicuousness of pigmented skin lesions may lead patients to seek care earlier than those with nonpigmented BCCs.
Punch biopsy of our patient revealed multiple small irregular islands, micronodules, and strands of atypical basal cells that diffusely infiltrate the dermis with a prominent desmoplastic stromal response, confirming a diagnosis of PBCC. After speaking to her about her diagnosis, she denied a history of radiation exposure. Our patient was subsequently sent to a Mohs specialist for excision of the large plaque but was lost to follow up.
The morphology of PBCC can be similar to melanoma. Distinguishing the two diagnoses often cannot be made by gross visualization or dermoscopy alone. There should be a low threshold for biopsy if either diagnosis is suspected.
Unfortunately, physicians do not generally associate skin cancer with persons of color, as public awareness has focused on the higher risk White population. This is compounded by the fact that pigmented lesions can be challenging to examine in dark skin for the unfamiliar practitioner, leading to misdiagnosis, erroneous treatment, and late presentation.1 For this reason, mortality and morbidity among blacks with skin cancer remains disproportionately high in comparison to whites.5
Dr Ahn is a general medical officer in the Army. Dr Aziz is staff dermatologist at Washington DC Veterans Affairs Medical Center and assistant professor of dermatology at Howard University in Washington, DC.
Disclosure: Dr Ahn reports no relevant financial relationships. Dr Aziz is employed by Howard University College of Medicine and Washington DC Veterans Affairs Medical Center.
1. Halder RM, Bridgeman-Shah S. Skin cancer in African Americans. Cancer. 1995;75(S2):667-673. doi:10.1002/1097-0142(19950115)75:2+<667::aid-cncr2820751409>3.0.co;2-i
2. Mora RG, Burris R. Cancer of the skin in Blacks: a review of 128 patients with basal-cell carcinoma. Cancer. 1981;47(6):1436-1438. doi:10.1002/1097-0142(19810315)47:6<1436::aid-cncr2820470632>3.0.co;2-b
3. Maloney ME, Jones DB, Sexton FM. Pigmented basal cell carcinoma: investigation of 70 cases. J Am Acad Dermatol. 1992;27(1):74-78. doi:10.1016/0190-9622(92)70160-H
4. Beckenstein MS, Windle BH. Basal cell carcinoma in Black patients: the need to include it in the differential diagnosis. Ann Plast Surg. 1995;35(5):546-548. doi:10.1097/00000637-199511000-00020
5. Gloster H, Neal K. Skin cancer in skin of color. J Am Acad Dermatol. 2006;55(5):741-760. doi:10.1016/j.jaad.2005.08.063
6. Tezuka T, Ohkuma M, Hirose I. Melanosomes of pigmented basal cell epithelioma. Dermatology. 1977;154(1):14-22. doi:10.1159/000251025
7. Bleehen SS. Pigmented basal cell epithelioma. Br J Dermatol. 1975;93(4):361-370. doi:10.1111/j.1365-2133.1975.tb06509.x
8. Menzies SW, Westerhoff K, Rabinovitz H, Kopf AW, McCarthy WH, Katz B. Surface microscopy of pigmented basal cell carcinoma. Arch Dermatol. 2000;136(8):1012-1016. doi:10.1001/archderm.136.8.1012
9. McCormack CJ, Kelly JW, Dorevitch AP. Differences in age and body site distribution of the histological subtypes of basal cell carcinoma. Arch Dermatol. 1997;133(5):593-596. doi:10.1001/archderm.1997.03890410049006
10. James WD, Elston DM, Berger TG. Pigmented basal cell carcinoma. In: Andrews Diseases of the Skin: Clinical Dermatology. Elsevier; 2016:789-790.
11. Ortonne N, Wechsler J, Bagot M, Grosshans E, Cribier B. Granuloma faciale: a clinicopathologic study of 66 patients. J Am Acad Dermatol. 2005;53(6):1002-1009. doi:10.1016/j.jaad.2005.08.021
12. Muhlbauer J. Granuloma annulare. J Am Acad Dermatol. 1980;3(3):217-230. doi:10.1016/S0190-9622(80)80181-2
13. O’Brien JP. Actinic granuloma. An annular connective tissue disorder affecting sun- and heat-damaged (elastotic) skin. Arch Dermatol. 1975;111(4):460-466. doi:10.1001/archderm.111.4.460
14. Aoyagi S, Nouri K. Difference between pigmented and nonpigmented basal cell carcinoma treated with Mohs micrographic surgery. Dermatol Surg. 2006;32(11):1375-1379. doi:10.1111/j.1524-4725.2006.32309.x