Pityriasis rosea

Pityriasis rosea is a viral rash which lasts about 6–12 weeks. It is characterised by a herald patch followed by similar, smaller oval red patches that are located mainly on the chest and back.Pityriasis rosea most often affects teenagers and young adults. However, it can affect males and females of any age.Many people with pityriasis rosea have no other symptoms, but the rash sometimes follows a few days after a upper respiratory viral infection (cough, cold, sore throat or similar).

The herald patch

The herald patch is a single plaque that appears 1–20 days before the generalised rash of pityriasis rosea. It is an oval pink or red plaque 2–5 cm in diameter, with a scale trailing just inside the edge of the lesion like a collaret.

Secondary rash

A few days after the appearance of the herald patch, more scaly patches (flat lesions) or plaques (thickened lesions) appear on the chest and back. A few plaques may also appear on the thighs, upper arms and neck but are uncommon on the face or scalp. These secondary lesions of pityriasis rosea tend to be smaller than the herald patch. They are also oval in shape with a dry surface. Like the herald patch, they may have an inner collaret of scaling. Some plaques may be annular (ring-shaped).

Pityriasis rosea plaques usually follow the relaxed skin tension or cleavage lines (Langers lines) on both sides of the upper trunk. The rash has been described as looking like a fir tree. It does not involve the face, scalp, palms or soles.

Pityriasis rosea may be very itchy, but in most cases it doesn't itch at all.iPtyriasis rosea is associated with reactivation of herpes viruses 6 and 7, which cause the primary rash roseola in infants.Pityriasis rosea clears up in about six to twelve weeks. Pale marks or brown discolouration may persist for a few months in darker skinned people but eventually the skin returns to its normal appearance.Pityriasis rosea during early pregnancy has been reported to cause miscarriage in 8 of 61 women studied. Premature delivery and other perinatal problems also occurred in some women.

General advice

• Bathe or shower with plain water and bath oil, aqueous cream, or other soap substitute.
• Apply moisturizing creams to dry skin.
• Expose skin to sunlight cautiously (without burning).
• acyclovire for some

Pyoderma gangrenosum

Pyoderma gangrenosum is an uncommon, ulcerative cutaneous condition of uncertain etiology. It is associated with systemic diseases in at least 50% of patients who are affected.The diagnosis is made by excluding other causes of similar-appearing cutaneous ulceration, including infection, malignancy, vasculitis, collagen vascular diseases, diabetes, and trauma. 

The prognosis of pyoderma gangrenosum is generally good; however, the disease may recur, and residual scarring is common. Pain is a common complaint of patients and may require narcotics.Other organs systems that may be involved include the heart, the central nervous system, the gastrointestinal (GI) tract, the eyes,^{[4, 5]} the liver, the spleen, the bones, and the lymph nodes.

Most patients with pyoderma gangrenosum improve with initial immunosuppressive therapy and require minimal care afterwards. However, many patients follow a refractory course, and multiple therapies may fail. These patients pose a difficult clinical problem that requires frequent follow-up and long-term care.

Tenia versicolor 

his title designates a superficial fungal infection (tinea) that changes color (versicolor). The causative organism was originally called Malassezia furfur and is now called Pityrosporum orbiculare. TV typically causes numerous patchy scally macules on the upper chest and back,  arms, and neck. Facial involvement may occur as shown. The lesions may behypopigmented  as illustrated here, or brown-orange, depending on th e skib color of the patient and the degree of recent sun exposure. The organism is believed to prevent either the formation of melanin or the transfer of melanosomes into keratinocytes. The formation of azelaic acid is another suggested mechanism for the resultant hypopigmentation. Although tinea versicolor usually makes its appearance after puberty, it can develop in child and is occasionally seen in breast-fed infants. Tinea versicolor is usually asymptomatic  but may itch slightly. The organism cannot be cultured, but diagnosis is aided by the orange or brown glow of lesional skin under a Wood's light and by the “spaghetti and meatballs” appearance of clustered hyphae and spores on KOH.