Patient presents 2 wks after an attack of acute Streptococcal tonsillitis. What is the most likely diagnosis, assuming this rash appeared before any antibiotics were instituted. Hint: this boy is 12 yrs old...an age at which scarlet fever is unlikely and let's assume he has been immunized for measles Differentials are welcome.
Correction - I incorrectly mentioned 1 wk after streptococcal tonsillitis..it is actually 2 weeks. within a week of onset of sterp tonsillitis or pharyngitis ...scarlet fever is the most likely answer. Hint: this boy is 12 yrs old...an age at which scarlet fever is unlikely
As per my original post - scarlet fever is valid within 1 week of strep pharyngitis or tonsillitis and bacterial infections can cause superimposed viral infections due to decreased immunity ex - measles after repeated diarrheal infections or URTI esp. in the developing world. Let's assume that our patient has been immunised against Measles....
Answer: Guttate psoriasis Discussion Preface A number of valid differentials have been posted and I will agree that some seem more correct than the actual diagnosis in this case. I will keep the differentials first and then elaborate on them. Management however is a matter of responding to symptoms to diminish discomfort for most of the differentials below and specific Mx wherever warranted or is beneficial will be mentioned. Pleas note, that most of these morbilliform rashes mimic each other so closely that even a seasoned dermatologist will be at his wits end, trying to make a diagnosis just based on morphology. Often it's the Hx which helps in arriving at a probable diagnosis. Secondly looking for primary or early lesions in the sea of secondary or fully evolved lesions can add significantly to pinning the diagnosis on physical exam. Examining in good light ( that mics day light ) and a magnifying glass can bring out the subtleties in morphology ex. the fine peripheral collarete in P rosea. Differentials Related to the acute attack of tonsillitis and assuming that there is no impairment with immunity a) Guttate psoriasis is the most likely possibility if the rash is delayed by 2 weeks or more of the onset of acute sterp throat infection ( pharyngitis or tonsillitis ) Guttate psoriasis shows shower of small lesions, appearing more or less generally over the body, particularly in children and young adults, and after acute streptococcal infections. In the early stages, there may be little scaling. The lesions are from 2 or 3 mm to 1 cm in diameter, round or slightly oval. They are scattered more or less evenly over the body, particularly on the trunk and proximal part of the limbs, rarely on the soles but not infrequently on the face, ears and scalp. The lesions on the face are often sparse, difficult to see and disappear quickly. Although guttate lesions are normally profuse, there are occasionally no more than half a dozen present on the body, and in the early stages the colour is not specific. The diagnosis is made chiefly on the nature of the scaling, the general distribution and evidence for preceding infection. There is evidence that streptococcal infection may be important in chronic plaque psoriasis, and that treatment with rifampicin and penicillin may lead to clearance of skin lesions. Further, acute episodes of guttate psoriasis are much more common in individuals with a family history of plaque psoriasis and one-third of cases of guttate psoriasis progress to the chronic plaque form. Guttate and chronic plaque psoriasis share strong HLA associations, particularly with HLA-Cw6. ref - Rook's textbook of dermatology, Chapter 20 b) If the rash were to appear within a few days ( and certainly less than a week ) of onset of acute tonsillitis in a child less than 8 years - it goes in favor of scarlet fever. The rash of scarlet fever appears within 2 to 3 days after the onset of streptococcal tonsillitis or pharyngitis. Initial systemic symptoms can include fever, malaise, and a sore throat. The rash begins 12 to 48 hours later with punctate lesions (goose pimples), become confluently erythematous (i.e.scarlatiniform), and linear petechiae (Pastia’s sign) can occur in body folds. The rash usually appears first on the neck and face, often leaving a clear unaffected area around the mouth (perioral pallor). It then spreads to the chest and back and finally to the rest of the body. In the body creases, especially around the axillae (underarms) and elbows, the rash forms the classic red streaks known as Pastia lines. On very dark skin, the streaks may appear darker than the rest of the skin. Areas of rash usually turn white (or paler brown, with dark complected skin) when pressed on. By the sixth day of the infection, the rash usually fades, but the affected skin may begin to peel( brawny desquamation ). THe rash is becos of erythrogenic toxin. The tongue initially is white with scattered red swollen papillae (white strawberry tongue). By the fifth day, the hyperkeratotic membrane is sloughed and the lingular mucosa appears bright red (red strawberry tongue). ref - color atlas and synopsis of Pediatric Dermatology Viral exanthems which can occur independently of the bacterial infection ( with or without predisposition ) a) Rubella - After an incubation period of 14”“21 days, German measles causes symptoms that are similar to the flu. The primary symptom of rubella virus infection is the appearance of a rash (exanthem) on the face which spreads to the trunk and limbs and usually fades after three days (that is why it is often referred to as three-day measles). The facial rash usually clears as it spreads to other parts of the body. Other symptoms include low grade fever, swollen glands (sub occipital & posterior cervical lymphadenopathy), joint pains, headache and conjunctivitis.The swollen glands or lymph nodes can persist for up to a week and the fever rarely rises above 38 oC (100.4 oF). The rash of German measles is typically pink or light red. The rash causes itching and often lasts for about three days. The rash disappears after a few days with no staining or peeling of the skin. When the rash clears up, the skin might shed in very small flakes where the rash covered it. Rubella virus specific IgM antibodies are present in people recently infected by Rubella virus but these antibodies can persist for over a year and a positive test result needs to be interpreted with caution. The presence of these antibodies along with, or a short time after, the characteristic rash confirms the diagnosis. ref - wiki b) Measles - Definitely a risk in the unimmunised and more number of adults who reportedly had chilhood vaccination are now presenting with measles. After an incubation period of about 10 days, the prodromal symptoms of fever, malaise and upper respiratory catarrh begin acutely. The conjunctivae are injected and there may be photophobia. From the second day, Koplik’s spots are usually present on the buccal mucous membrane opposite the premolar teeth—bluish white spots with bright-red areolae.Fever, catarrh and cough increase for 3”“5 days. The exanthem characteristically develops on the fourth day on the forehead and behind the ears, and spreads within 24 h to the rest of the face, the trunk and the limbs. The rash is at first macular but soon forms dull red papules which tend to coalesce in irregularly concentric patterns but may be more diffusely confluent. From the sixth to the tenth day the rash fades, to leave some brownish staining and fine desquamation. In very severe forms it may be haemorrhagic. An extensive bullous eruption may rarely develop during the acute stage of measles. In some cases this eruption has the features of Stevens”“Johnson syndrome, but in others it resembles epidermal necrolysis. Complications are more common in young children, the malnourished and the chronically ill. ref- Rook's textbook of Dermatology Note: As in measles, the rubella rash appears as immunity develops and the virus disappears from the blood,suggesting that the rash is immunologically mediated. It's no surprise then that immunocompromised children don't show the typical rash but are more prone to complications such as meningo-encephalitis and pneumonia. Although circulating immune complexes are detectable during rubella, they do not appear to contribute to the development of rash. c) Pitryiasis rosea - if there has been a concurrent viral infection, then one could get a rash of Pitryiasis rosea 2 - 4 weeks down the line. Distribution: Trunk > proximal arms, legs. Head, face typically spared. It usually begins as a herald salmon colored patch which then evolves to develop a collarette of scales on the periphery ( very pathognomic ). This is followed (within hours to weeks ) by an extensive rash on the trunk (esp. on the back) which is distributed along the clevage lines, famously called the 'Christmas Tree pattern'and with time many of the individual lesions will develop the fine collarette of scales as seen in the 'herald patch'. A closer look (with magnifying glass) also showsthese lesions to be oval in shape with the long axis arranged along the clevage lines. The rash (seen in 70 - 80 % patients) is moderate to intensely pruritic and resolves within 6 - 8 weeks. Rx can be with Calamine lotion, topical steroids, oral antihistaminics, topical menthol-phenol lotions and oatmeal baths.Systemic steroids are not recommended, because although they may decrease pruritis, they may prolong the disease course. In cases that are not controlled by these measures UVB light therapy has shown to alleviate symptoms. Note : 1) Pitryiasis rosea has also been reported to appear after the use of certain drugs ex. metronidazole, isotretinoin, clonidine, aspirin, omeprazole etc. 2) In atypical PR or at-risk individuals, an RPR should be checked because secondary syphilis can have a similar presentation. Contd in next post ( due to image restrictions per post )
other possibilities Less common but serious conditions mimicking pityriasis rosea and guttate psoriasis are secondary syphilis and HIV seroconversion and needs to be considered in sexually active adolescents. Secondary syphilis Consider the possibility of secondary syphilis if there are lesions on the palms and the soles of the feet, or generalized lymphadenopathy, in people who are sexually active. Lesions are non-itchy and coppery red. They are symmetrically distributed along cleavage lines (as in pityriasis rosea) and occur around 8 weeks after primary syphilis (when a chancre will have been present).The rash is accompanied by fever, headache, and bone and joint pains (which are more pronounced at night).Lesions are initially macular and become papular by 3 months. The macules are round or oval, and non-scaly. Papules are firm, round or oval, and less than 0.5–2 cm in diameter. Early papules tend to be shiny, but gradually a thin layer of scale forms. Older lesions tend to be pigmented and very scaly. HIV seroconversion can also present with an erythematous maculopapular rash similar to pityriasis rosea. The rash consists of round or oval lesions (5 mm to 3 cm in diameter), which may be slightly raised. The rash is distributed symmetrically on the face, trunk, palms, and soles, and typically lasts for 1–3 weeks. The rash is almost always accompanied by a febrile, influenza-like illness (whereas pityriasis rosea & guttate psoriasis may be preceded by such an illness). Arthropod borne Viral infections ex - Dengue fever & Chikungunya Nummular Eczema: Cutaneous eruption characterized by discoid or coin-shaped plaques of eczema. The lesions usually occur on the extensor surfaces of the extremities, but the face and trunk may also be involved. The specific aetiology is unknown. However, it seems to appear in a cold and dry environment and is aggravated by excessive bathing and local irritants such as wool. Often, a heavy colonisation of the lesions by staphylococci has been found. ref - DermIS - Nummular Eczema (information on the diagnosis) etc (end of thinking capacity) :grin:
