However, a potassium hydroxide preparation can help rule out the presence of a fungal infection. Imaging and biopsy are not necessary. Differential diagnosis
Acid
Athletes foot (Tinea pedis)
Erythrasma
Hyperhidrosis

Treatment
As of 2014, there is little high-quality evidence to provide guidance and support one treatment method over another. Therefore, the optimal treatment approach for pitted keratolysis remains unclear as the condition has not been well-studied. One review suggested a treatment approach requiring modification of risk factors (e.g., keeping feet clean and dry) and treating the underlying bacterial infection. Effective antibiotic options include clindamycin, erythromycin, mupirocin, and fusidic acid. Topical clindamycin is generally preferred as the first-line choice due to lower cost and better availability. Fusidic acid is preferred over mupirocin in most cases due to less resistance to fusidic acid amongst Methicillin-sensitive staphylococcus aureus and Methicillin-resistant staphylococcus aureus. Benzoyl peroxide is an effective alternative over-the-counter option and is thought to be as effective as topical clindamycin. Clinical cure was typically seen after 2.5–3 weeks. Oral antibiotics are not typically recommended.Foot hygiene is important. The feet may be washed at least daily with soap and water, and dried thoroughly afterwards. Moisture-wicking socks and shoes may be worn and antiperspirants, such as aluminum chlorohydrate, may help to keep the feet dry. Injections of botulinum toxin have successfully induced cessation of sweating (anhidrosis) of the soles of the feet and led to resolution of pitted keratolysis.
Vasculitic neuropathy is a peripheral neuropathic disease. In a vasculitic neuropathy  there is damage to the vessels that supply blood to the nerves. It can be as part of a systemic problem or can exist as a single-organ issue only affecting the peripheral nervous system (PNS). It is diagnosed with the use of electrophysiological testing, blood tests, nerve biopsy and clinical examination. It is a serious medical condition that can cause prolonged morbidity and disability and generally requires treatment. Treatment depends on the type but it is mostly with corticosteroids or immunomodulating therapies. Types
There are three main categories of vasculitic neuropathies: primary, secondary and non-systemic. Primary systemic vasculitic neuropathy
Some patients with systemic vasculitis will have their multi-organ disease spread to the peripheral nervous system; this is primary vasculitic neuropathy. Some examples of systemic vasculitic disease are: IgA vasculitis, Hypocomplementemic urticarial vasculitis, polyarteritis nodosa (PAN) and anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitides such as granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA) and microscopic polyangiitis (MPA). Vasculitic neuropathy secondary to other disease
Some patients with a non-vasculitic systemic disease or another illness such as infection or malignancy can subsequently develop vasculitic neuropathy as a direct consequence of the former illness; this is secondary vasculitic neuropathy. Some examples of such illness which can cause vasculitic neuropathy are:
Connective tissue diseases: rheumatoid arthritis, systemic lupus erythematosus, primary sjögrens, dermatomyositis. Infectious diseases: hepatitis B, hepatitis C, human immunodeficiency virus (HIV), cytomegalovirus, lyme disease, human T-cell-lymphotrophic virus-I, parvovirus B19. Malignancy. Drugs (amphetamines, sympathomimetics, cocaine, etc.) Vaccinations.