Toxic Epidermal Necrolysis (TEN) Workup

Updated: Jun 07, 2022
  • Author: Samantha P Jellinek-Cohen, PharmD, BCPS (AQ-ID); Chief Editor: Michael Stuart Bronze, MD  more...
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Approach Considerations

TEN is a clinical diagnosis, confirmed by histopathologic analysis of lesional skin. Early involvement of a dermatologist and dermatopathologist is recommended. Skin biopsy, harvested at the earliest possible stage, is important in establishing an accurate diagnosis and directing specific therapeutic modalities.

Necrotic keratinocytes with full-thickness epithelial necrosis and detachment is consistent with the diagnosis of TEN. Perivascular and scattered lymphocytic infiltration of the dermis is sometimes demonstrated, although the underlying dermis is not greatly altered.

No definitive or specific emergent laboratory tests are indicated for TEN. Basic laboratory tests may be helpful in planning symptomatic or supportive therapy. Surveillance cultures of blood, skin, and urine should be obtained.

Imaging studies are not indicated for the diagnosis of TEN. Chest radiography should be performed in the setting of respiratory distress because tracheobronchial inflammation may predispose to diffuse interstitial pulmonary disease or pneumonia.


Blood Studies

Hematology studies include the following:

  • Complete blood count (CBC) and differential

  • Circulating immune complexes

  • Erythrocyte sedimentation rate

Leukopenia is common, whether a result of TEN itself or of bacteremia, as is a normochromic normocytic anemia. Eosinophilia may be present. Less often, thrombocytopenia, neutropenia, and bandemia may occur. Neutropenia is an unfavorable prognostic sign.

In the acute phase, there are transient decreases of peripheral CD4+ T lymphocytes and reduced allogeneic and natural killer cell cytotoxicity, which returns to normal in 7-10 days.

Coagulation studies may include prothrombin time/international normalized ratio (INR) and activated partial thromboplastin time.

Chemistry to assess fluid and electrolyte losses include the following:

  • Albumin

  • Blood urea nitrogen

  • Total protein

As toxic epidermal necrolysis progresses, multiple organs are affected, causing other abnormalities in laboratory test results. Diffuse skin involvement may cause significant fluid loss and electrolyte abnormalities.



A skin biopsy specimen must be obtained. In experienced hands, a frozen section specimen expedites matters. Results are very useful in differentiating TEN from other dermatologic disorders.

Histologically, TEN is characterized by full-thickness epidermal necrosis with little evidence of epidermal or dermal inflammation. Epidermal detachment and sloughing may be evident. Satellite cell necrosis may be visible early, progressing to extensive eosinophilic necrosis.


Other Tests

Patch testing may be used to identify the culprit drugs. [47]  Patch tests show an acceptable sensitivity, yielding positive results in 50% of patients with acute generalized exanthematous pustulosis and in 50% of patients with maculopapular exanthema.