From the Guidelines
Yes, black flat macules can appear suddenly on the arms, and one possible cause is post-kala-azar dermal leishmaniasis (PKDL), which can occur after treatment of visceral leishmaniasis, as noted in a study published in Clinical Infectious Diseases 1. These skin lesions may represent various conditions, including seborrheic keratoses, solar lentigines (sun spots), post-inflammatory hyperpigmentation, or more concerning conditions like melanoma. If you notice new black spots appearing suddenly, especially if they are changing in size, shape, or color, you should consult a dermatologist promptly for evaluation. Concerning features include asymmetry, irregular borders, multiple colors, diameter larger than 6mm, or evolution over time (the ABCDE rule for melanoma). Some benign causes like post-inflammatory hyperpigmentation can follow skin injury or inflammation, while sun spots develop from cumulative sun exposure. Seborrheic keratoses often appear with age and can seem to develop suddenly even though they grow slowly. While many black macules are harmless, only a medical professional can properly diagnose them through visual examination and sometimes biopsy. Protecting your skin from sun exposure by using broad-spectrum sunscreen and wearing protective clothing can help prevent some types of pigmented lesions. Key points to consider when evaluating black flat macules on the arms include:
- Sudden appearance or changes in existing lesions
- Presence of other symptoms such as fever, weight loss, or fatigue, which could indicate a more serious underlying condition like visceral leishmaniasis 1
- History of travel to or residence in areas where leishmaniasis is endemic
- Family history of similar skin lesions or other medical conditions.
From the Research
Black Flat Macules on Arms
- Black flat macules can appear on various parts of the body, including the arms, due to different conditions.
- According to the study 2, macular amyloidosis (MA) can present with multiple, discrete, brownish macules on the arms, although it typically appears on the legs, arms, and upper back.
- Another study 3 describes telangiectasia macularis multiplex acquisita, characterized by multiple asymptomatic erythematous and/or brownish macules with telangiectasias, preferably on bilateral upper arms and trunk.
- However, there is no direct evidence in the provided studies that specifically mentions black flat macules appearing suddenly on the arms.
- The study 4 discusses physiologic volar melanotic macules, which are common in individuals with skin of color, but these macules are typically found on the palms and soles, not the arms.
- The study 5 mentions various skin variations normally found in blacks, including plantar hyperpigmented macules, but does not specifically discuss black flat macules on the arms.
- The study 6 describes amalgam tattoo, which can present as a dark gray or blue, flat macule, but this is typically found in the oral mucosa, not on the arms.