TABLE 2.
Histopathologic findings of COVID‐19‐induced chilblains
| % of patients (n = 21) with this finding present or absent | |||
|---|---|---|---|
| Present | Absent | ||
| Epidermal changes | Acanthosis | 86 | 14 |
| Hyperkeratosis | 100 | 0 | |
| Parakeratosis |
14 (upper) 43 (lower) |
43 | |
| Parakeratosis with exudate |
38 (moist) 19 (dry) |
43 | |
| Spongiosis | 33 | 67 | |
| Exocytosis | 48 | 52 | |
| Interface dermatitis | Vacuolar interface |
62 (focal) 19 (diffuse) 19 (continuous) |
0 |
| Number of apoptotic keratinocytes (×20) |
48 (1 keratinocyte) 38 (2–3 keratinocytes) 14 (≥4 keratinocytes) |
0 | |
| Basal membrane thickening |
48 (focal) 10 (diffuse) |
42 | |
| Lichenoid infiltrate | 0 | 100 | |
| Pigmentary incontinence | 5 (focal) | 95 | |
| Papillary dermal changes | Papillary dermal edema | 28 | 72 |
| Red cell extravasation | 76 | 24 | |
| Fibrin deposition | 14 | 86 | |
| Lymphocytic vasculitis | Perivascular lymphocytic infiltrate |
14 (discrete) 43 (moderate) 43 (intense) |
0 |
| Post‐capillary venule wall infiltration | 86 | 14 | |
| Swollen endothelial cells | 57 | 43 | |
| Vessel wall thickening | 86 | 14 | |
| Fibrin deposition | 5 (focal) | 95 | |
| Red cell extravasation | 43 | 57 | |
| Intraluminal thrombi formation | 5 (focal) | 95 | |
| Lymphocytic infiltrate | Superficial infiltrate | 95 | 5 |
| Deep infiltrate | 95 | 5 | |
| Distribution |
21 (top heavy) 5 (bottom heavy) |
74 (no difference) | |
| Perivascular |
14 (discrete) 43 (moderate) 43 (intense) |
0 | |
| Interstitial |
48 (discrete) 24 (moderate) 10 (intense) |
18 | |
| Peri‐eccrine |
42 (discrete) 26 (moderate) 26 (intense) |
6 | |
| Other | Interstitial mucin deposition |
71 (focal) 29 (diffuse) |
0 |
| Peri‐eccrine mucin deposition |
25 (focal) 71 (diffuse) 25 (intense) |
5 | |
| Collagen necrobiosis | 0 | 100 | |
| Subcutaneous infiltration |
31 (discrete) 31 (moderate) 7 (intense) |
31 | |
Notes: A skin biopsy was performed in 24 patients, but three patients were excluded because of a positive ANA. Thus, 21 patients are reported. Of note, the exclusion of these three patients did not statistically affect our results. Each histopathologic feature is recorded as “Present” or “Absent” in a percentage of the patients. Subcharacteristics are noted in parentheses.