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Itchy skin disease

Blistering case challenge

A 44-year-old woman presents with a widespread eruption that has developed over the last week. She is otherwise well and takes no medications.

Which terms best describe the configuration of the eruption? # Target # Reticulated # Gyrate #! Annular || Lesions grouped in a circle. Multiple rings are “polycyclic”. Which terms best describe the configuration and morphology of the eruption? # Nodule #! Bulla || Large fluid-filled blister. It may be a single compartment or multiloculated. # Weal # Plaque

The patient has an extensive blistering disease and is referred urgently to a dermatologist for diagnosis and treatment.

Which of the following procedures did the dermatologist perform to determine the cause of the eruption? * Skin swab * Skin scrapings *! Skin biopsy * Patch testing for contact allergy Explanation: The dermatologist performed a skin biopsy. Had there been signs of secondary skin infection (impetigo or cellulitis), skin swabs would have also been taken for microscopy and culture. Although fungal infections sometimes result in vesicles and pustules, they do not result in a widespread blistering rash so skin scrapings are unnecessary. Severe contact allergy can result in blistering with other signs of dermatitis and was not considered likely in this case. Which of the following types of biopsy is appropriate? * Needle core biopsy * Endoscopic biopsy * Shave biopsy *! Punch biopsy Explanation: In this case, the dermatologist did 4mm punch biopsies of a two typical small blisters on the patient’s upper arm. Explanation: A needle core biopsy removes a tiny core of tissue and is used for internal organs such as the liver and kidney. Endoscopic biopsies are taken using an endoscope, which is unnecessary for the skin! A shave biopsy is used to remove or flatten out a protruding lesion. The tops of the blisters illustrated could be removed by shaving but would not provide material suitable for diagnosis. Which of the following tests were requested? #! Histopathology # Cytology #! Direct immunofluorescence # Immunohistochemistry Explanation: Skin biopsies are processed for routine histopathology. Specific patterns of deposition of immunoglobulins characterise blistering diseases, identified by direct immunofluorescence. Cytology is not routinely employed for skin specimens. Immunohistochemistry is often helpful in the diagnosis of tumours and infections, and is sometimes used in inflammatory skin diseases for research purposes. Explanation: Each biopsy was put in a separate specimen container containing a special solution.

Have a look at the online Waikato Hospital laboratory handbook to see which solutions are recommended for skin biopsies for immunofluorescence studies.

Which of the following solutions were used? #! RPMI #! 10% formol saline # Cytofix # Normal saline Explanation: One sample (labeled A) was immersed in 10% Formal Saline fixative for routine histology and the other sample (B) was placed in RPMI transport solution for immunofluorescence. Explanation: If specific transport solution is unavailable, the sample can be snap frozen in liquid nitrogen.

A request form for pathology specimens is illustrated.

Histopathology form

To obtain the most useful diagnostic opinion from the pathologist, all sections of the form should be carefully completed.

The patient’s name, identification number, date of birth and sex are required as well as the name of the doctor requesting the test, and the names of any other doctors who should receive a copy of the report. The time and date that the biopsy was performed should be added to the appropriate spot.

Select the most suitable information for the "NATURE OF SPECIMEN / SITE" section of the form. Short answer: The "NATURE OF SPECIMEN / SITE" should indicate that it's a skin biopsy and what type, and where it came from. If there is more than one, they should be identified to match the labels on the respective pots. The dermatologist completed the form as follows: 1. Punch biopsy left upper arm (medial) 2. Punch biopsy left upper arm (lateral), for direct immunofluorescence.

The completed form and the specimens were placed in a biohazard bag and transported to the laboratory within an hour.

Type in brief “CLINICAL DETAILS”. Short answer: Clinical data should outline the presenting complaint, the clinical diagnosis or differential diagnosis and any other relevant information. ‘Rash’ or ‘lesion’ is not adequate! If the biopsy relates to another specimen, record this with its laboratory reference number if known. In this case the dermatologist wrote: Explanation: Very extensive bullous eruption 5 days; huge tense blisters on trunk and limbs ?immunobullous disease

The completed form and the specimens were placed in a biohazard bag and transported to the laboratory within an hour.

The date, type and site of the procedure were recorded in the theatre book and in the clinical notes.

Here are low- and medium-power views of haematoxylin and eosin stained sections.

How would you describe this? *! Subepidermal blister * Intraepidermal blister * Marked inflammatory response * Minimal inflammatory response Explanation: Sections show a subepidermal vesicle, which is filled with eosinophilic fluid and contains quite large numbers of eosinophils. The superficial dermis beneath the vesicle contains a sparse perivascular lymphohistiocytic infiltrate with occasional eosinophils. Tissue has been sent for fluorescence microscopy.

Direct immunofluorescence testing is useful to identify subepidermal blistering diseases.

Bullous disease Immunofluorescent staining pattern
Bullous Pemphigoid Linear deposition of IgG +/- C3 at BMZ
Linear IgA Disease Linear deposition of IgA at BMZ
Dermatitis Herpetiformis Granular IgA deposition at BMZ
Erythema Multiforme (dermal type) Negative
Fixed Drug Eruptions (dermal type) Negative
Epidermolysis Bullosa Negative

The immunofluorescence staining pattern for this patient is shown below:

Normal control

Patient's skin biopsy


IgA is predominantly deposited in which location? * Subcorneal * Intraepidermally *! Linear deposition BMZ * Granular deposition BMZ

The report for direct immunofluorescence stated:

Immunofluorescence of skin biopsy shows a classical linear deposition of IgA along the epidermal basement membrane.

What is the best diagnosis? * Bullous pemphigoid * Porphyria cutanea tarda *! Linear IgA dermatosis * Epidermolysis bullosa Explanation: The patient has linear IgA dermatosis characterised by typical clinical and histological features. This is a rare immunobullous disease and may be very challenging to treat.

The images below were taken three days after initial presentation. Nine months later she continues to have widespread cutaneous and intraoral erythematous plaques, blistering, and erosions despite treatment with moderate dose oral corticosteroids and a series of anti-inflammatory and immunosuppressive medications that were either ineffective (erythromycin, cotrimoxazole, methotrexate) or resulted in drug-induced subclinical hepatitis (dapsone, azathioprine).