Lower extremity dermatology in skin of colour
Lower extremity dermatology in skin of colour
Particular care needed in history-taking, physical examination of skin issues of the legs and feet (1,400 words, 7 minutes)
There is a shortage of literature on dermatology in patients with skin of colour, and even less that focuses on the skin of the lower extremities.
This was the focus of a roundtable discussion published by Podiatry Today (Sept. 2023).
G. “Dock” Dockery, DPM, FACFAS, said he has observed some general dermatology publications addressing skin of colour. However, those publications mostly detail conditions of the head, neck, and trunk. Dr. Dockery is Founder, Chairman, and President of the International Foot & Ankle Foundation for Education and Research.
As part of their discussion, the panellists discussed aspects of history-taking and physical exam findings that are particularly important when evaluating lower extremity skin of colour.
Taking a patient’s personal and family history is vital when addressing skin issues in people of colour, particularly when the concerns relate to melanonychia, pigmented skin lesions, rashes, and skin cancer.
Lesly D. Robinson, DPM, CWSP, DABPM, added that it is important to know the patient’s healing and scarring history, as well as any information on keloid formation and skin hyperpigmentation. Any history of itchiness and tightness that can result from transepidermal water loss is also important to note, said Dr. Robinson, Chair of the Department of Podiatric Medicine at Temple University School of Podiatric Medicine in Philadelphia.
Signs of infection are a key consideration on a lower extremity dermatologic exam for patients with skin of colour, the panellists agreed. Alton R. Johnson, Jr., DPM, DABPM, said in a recent study he coauthored they found that based on clinical examination alone, clinicians were more likely to miss infections in patients with darker skin pigmentation, which they attributed to likely unconscious bias. Dr. Johnson is a Clinical Assistant Professor of Orthopaedic Surgery at the University of Michigan Medical School in Ann Arbor, Mich.
Variations in pigmentation should also be evaluated, the panellists said, to determine if it is natural variation or hyperpigmentation due to rash or proximity to a wound.
Optimizing the light source in the exam space is also important, as fluorescent lights can apply a bluish tint rather than showing colour accurately, the panel noted. Greater quantities of melanin in dark skin may also alter blanching in standard diascopy blanch testing, making the process of limited value in skin of colour.
Bottom line: The dermatologic literature on lower extremities in skin of colour is limited. Physicians should take extra care when collecting patient histories. During a physical exam, signs of infection and variations in pigmentation should draw the physician's attention. Proper lighting can help accurately evaluate skin colour.
From the literature on dermatology in the lower extremities
Near-infrared spectroscopy data for foot skin oxygen saturation in healthy subjects
Researchers evaluated normative data for near-infrared spectroscopy in 110 healthy volunteers by Fitzpatrick skin type (FST) and region of the foot. They gathered measurements of the dorsum and plantar foot using a commercially available device. On the dorsum of the foot, people with skin type VI had significantly lower oxygen saturation compared to skin types I-V (p<0.001), and lower oxyhemoglobin compared to skin types II-V (p=0.001). However, there was no difference in deoxyhemoglobin. No differences were found on the plantar foot. When comparing dorsal and plantar foot, there was higher oxyhemoglobin (0.40±0.09 vs. 0.51±0.12, p<0.001) and deoxyhemoglobin (0.16±0.05 vs. 0.21±0.05, p<0.001) on the plantar foot, but no differences in oxygen saturation (dorsal 70.7±10.8, plantar 70.0±9.5, p=0.414). In 6.4% of feet, there were black areas, for which no near-infrared measurements could be generated. All areas with no data were on the dorsal foot and only found in skin types V and VI. People with skin type VI had significantly larger areas with no data compared to skin type V (22.2 cm2±20.4 vs. 1.9 cm2±0.90, p=0.007).
The authors write their findings should be considered when using NIRS technology and that skin pigmentation should be evaluated in future studies of near-infrared spectroscopy.
Acral lentiginous melanoma with multiple bone metastasis: case report
The authors of this paper note that acral lentiginous melanoma (ALM) is traditionally seen on the soles of the feet, frequently diagnosed at late stages, and has higher incidences in non-White populations compared to the other forms of cutaneous malignant melanoma. The most common sites of metastases in melanoma are the skin and subcutaneous tissue followed by the lungs, liver, brain, and bone, they write. Bone metastases from malignant melanoma usually occur in patients who already have widespread metastases.
This case reports on an ALM lesion in an 84-year-old African American male presenting originally in the base of the right fifth toe plantar aspect. Multiple bone metastases were found without any other organ involvement.
Elephantiasis mimicry in recurrent lower limb skin infections in a diabetic patient: a case report
The patient described in this case was a 70-year-old Black man, bed-bound at the time of admission following a diagnosis of stroke and hypertension in the previous five years. He had been diabetic for 20 years with poorly controlled diabetes mellitus. He had recurrent bilateral lower limb skin infections for five years before admission that culminated in progressive lower limb edema. The infections progressed to skin edema, hardening, fissuring, and hyperkeratotic plaques.
Physical examination revealed Tinea pedis and bilateral non-pitting edema of lower limbs to the level of the knees. Investigations confirmed non-filarial lymphedema-related skin changes. The authors of the paper note the absence of the classic pebbly or cobblestone skin changes ruled out elephantiasis nostra verrucosa, with a possibility of it being in the early stages of development.
Skin fissuring and infections were successfully treated with antibiotics and antifungals while compression stockings helped to relieve the edema.
The authors write chronic lymphedema can complicate repeated non-filarial infections of the lower limbs. Fissures from lymphedema are a risk factor for cellulitis, prompting early identification and management of both infections and lymphedema to halt their vicious cycle, especially in at-risk populations such as diabetics.
Distinct presentation of melanoma in Black patients may inform strategies to improve outcomes
Using 2004 to 2019 Surveillance, Epidemiology, and End Results (SEER) data, researchers identified nonmetastatic melanoma patients with known tumour categories and race.
Of the 492,597 identified patients, 1,499 (0.3%) were non-Hispanic Black, who were younger (21% vs. 17% age <50) and more commonly female (54% vs. 41%) than non-Hispanic Whites, both p<0.0005.
For non-Hispanic Blacks, the lower extremity was the most common site for melanoma (52% vs. 15% for non-Hispanic Whites, p<0.0001), tumour (T) category was higher (55% Tis-T1 vs. 82%; 27% T3-T4 vs. 8%, p<0.0001) and stage at presentation was higher (19% Stage III, vs. 6%, p<0.0001).
Within the non-Hispanic Black cohort, investigators found males were older, and more often node-positive than females. Five-year Stage III cancer-specific survival was 42% for non-Hispanic Black males versus 71% for females, adjusting for age and clinical nodal status (hazard ratio 2.48).
VIDEO: Dissecting drivers of therapy resistance and metastases in acral lentiginous melanoma
In this University of Colorado Cancer Center symposium Vito W. Rebecca, PhD, details current research into the causes of poor outcomes in patients with acral lentiginous melanoma, the role of the plantar skin microenvironment in metastasis, and the role of the CDK4 pathway in these cancers. Dr. Rebecca is an assistant professor in the Department of Biochemistry and Molecular Biology at the Johns Hopkins Bloomberg School of Public Health in Baltimore.
At the intersection of skin and society
Canadian Heritage, a federal agency charged with fostering and promoting Canadian identity and values, cultural development, and heritage, has announced permanent funding to support the Indigenous Screen Office. According to a press release, this pledge includes $65 million over five years starting in 2024–25 and $13 million per year ongoing.
The release notes the Indigenous Screen Office is an independent, Indigenous-led organization that works to increase the presence of Indigenous storytelling on screen.
In 2022–23, the Office disbursed a total of $11.8 million in direct contributions to 191 recipients across 12 provinces and territories, including an additional $1.02 million in funding through strategic partnership programs.
“Securing ongoing funding marks a major milestone for the ISO and the Indigenous storytellers we support, and provides us all with a stable foundation from which to grow,” said Kerry Swanson, Chief Executive Officer of the Indigenous Screen Office, in the release. “This is only the beginning for the ISO as we embark on the full expression of our mandate to build an Indigenous screen sector in Canada, and for Indigenous-made stories on screen to inspire audiences around the world.”
This week
March 25 is The International Day of Remembrance of the Victims of Slavery and the Transatlantic Slave Trade
March 30 is Doctor’s Day in the U.S.
March 31 is International Trans Day of Visibility
Something to think about in the week ahead. . .
—Leo Rosten, American novelist, author of The Education of H*Y*M*A*N K*A*P*L*A*N (1908-1997)
Next week
Dr. Jaggi Rao of Edmonton discusses scalp psoriasis in patients with skin of colour, during a presentation at the 2023 Skin Spectrum Summit.
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Dr. Afsanah Alavi (Rochester, Minn.) details recent research showing a link between lower limb lymphedema and skin cancer.
Drs. Reetesh Bose (Ottawa), Morvarid Hessami (Toronto), and Marissa Joseph (Toronto) describe the establishment of dermatology clinics specializing in skin of colour, and the outcomes they are achieving.
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