The palmar and plantar desquamation of scarlet fever (SF) may follow a streptococcal pharyngitis or tonsillitis. SF typically begins with the abrupt onset of fever, sore throat, and a finely papular exanthem, with a distinctive “sandpapery” or “scarlatiniform” texture.

Toxic shock syndrome (TSS) is a systemic illness caused by infection with toxin-producing strains of Staphylococcus aureus or, less often, streptococci. Originally described in association with tampon use in women, TSS now occurs more commonly secondary to a local wound infection. Streptococcus and Staphylococcus can produce circulating toxins that cause clinical disease. Many of these toxins function as superantigens with resultant excessive production of pro-inflammatory cytokines and T cell proliferation, causing clinical symptoms that include fever, hypotension, and shock.

Kawasaki disease (KD), also known as mucocutaneous lymph node syndrome, is most often seen in those with Japanese ancestry. KD is a multisystem vasculitis that primarily affects infants and children. Evidence suggests an inhaled antigen triggers an immune response in genetically susceptible hosts. Symptoms include desquamation of the fingers and toes. (A similar multisystem inflammatory condition has been associated with COVID-19, especially in children [see Cutaneous Manifestations of COVID-19].)

Granuloma annulare (GA) is an idiopathic, generally asymptomatic, ring-shaped grouping of dermal papules. Proposed pathogenic mechanisms include cell-mediated immunity (type IV), immune complex vasculitis, and an abnormality of tissue monocytes. The papules are composed of focal granulomas that coalesce to form curious circles or semicircular plaques which can be easily misdiagnosed as “ringworm.” Rare cases persist for decades or longer.

GA is seen most frequently in young children in whom it is most often self-limiting. It also appears in adult women (female-to-male ratio is 2.5:1), in whom GA tends to be more chronic. There is an adult form of disseminated GA, which may be associated with diabetes.

Phytophotodermatitis, also known as berloque dermatitis, is a phototoxic reaction that results from contact with a photosensitizing agent followed by sun exposure. It is a phototoxic reaction from contact with certain plants. Its name has three components: phyto (plant), photo (light), and dermatitis (inflammatory eczematous rash).

The photosensitizing chemicals called furocoumarins are commonly found in several citrus fruits and plants, including lemons, limes, bergamot oranges, grapefruit, celery, parsley, parsnip, and hogweed.

The reaction is a chemically induced, nonimmunologic, acute skin reaction requiring sunlight. A botanical cause for dermatitis is suspected when the pattern of an eruption is linear or streaky, such as noted in the contact dermatitis caused by poison ivy. When the phytophotodermatitis is caused by perfume or other agents such as oil from the bergamot orange, an ingredient formerly contained in certain perfumes and fragrances, it is referred to as berloque dermatitis.

Solar lentigines, or “liver spots,” that appear on the sun-exposed dorsal hands, are often indistinguishable from seborrheic keratoses that also appear in this location. Solar lentigines are small, tan, oval to geometric shaped macules that are uniformly pigmented (Fig. 14-6). Seborrheic keratoses are flat or slightly palpable and may have a scaly or warty surface (Fig. 14-7).

Actinic keratoses (Fig. 14-8) and squamous cell carcinoma (Fig. 14-9) arise on the sun-exposed dorsal hands. They may be clinically indistinguishable from one another.

Hand eczema is a very common condition that is seen most often in those who have an underlying atopic predisposition. For descriptive purposes, Hand and foot eczema may be divided into two clinical presentations: a “wet” dyshidrotic type and a “dry,” hyperkeratotic, scaly type. The term dyshidrotic is a misnomer based on the erroneous assumption that the eczematous vesicles are caused by trapped sweat. We now understand that the vesicles result from inflammation and foci of intercellular edema (spongiosis), which becomes loculated in the thick stratum corneum.

Both endogenous hand eczema, where there is a personal or family history of atopy, and exogenous hand eczema, where irritants, allergens, or microbes are contributory factors, are often at work in the same patient.

Irritant contact dermatitis (ICD) and allergic contact dermatitis (ACD) are frequent occupational hazards. ACD is a delayed type IV hypersensitivity reaction that typically occurs days after exposure to a contactant such as solvents, oils, cement, metal (nickel), rings, topical medications, rubber gloves in surgeons, cosmetics, and countless other agents. Both ICD and ACD are also common concerns for those who work in industries that involve cleaning, hairdressing, painting, and metalwork. Eczema due to an irritant or allergen is less commonly seen on the palmar and plantar surfaces due to their much thicker stratum corneum than is found on the dorsal hands and feet.

Lesions of palmoplantar psoriasis may involve the palms and/or soles alone, or these areas may be a part of more extensive psoriasis that is also present elsewhere on the body. The involvement of the palms and soles often presents additional problems such as pain, impairment of function, fissuring, bleeding, and embarrassment. As with chronic hand eczema (described above), palmar psoriasis runs a chronic course and is often quite difficult to manage.