Table 1. Initial Clinical Diagnosis, Results of Microbiology and Histopathology, Final Classification, and Procalcitonin Results.

ID	Clinical Diagnosis	Prior Antibiotics	Culture	PCR	Histopathology	Final Diagnosis	Procalcitonin (ng/mL)
010	Cellulitis	-	MRSA	+	3–4+ deep dermal neutrophilic infiltrate consistent with cellulitis; Gram positive intracellular cocci	Bacterial cellulitis	undetectable
013	Cellulitis	-	α-hemolytic strep, Enterococcus sp.	+	Stasis dermatitis with mixed acute and chronic inflammation; Gram stain negative.	Bacterial cellulitis	undetectable
015	Cellulitis	-	MSSA from pustule	-	Superficial and deep perivascular and interstitial (into subcutis) mixed infiltrate (neutrophils and lymphocytes) consistent with cellulitis; Gram stain equivocal/negative.	Bacterial cellulitis	undetectable
003	Cellulitis	-	-	-	Consistent with lymphocytic vasculitis. The biopsy shows a permeative cuff surrounding several deep dermal/subcutaneous vessels, as well as an overlying lymphocytic infiltrate surrounding the eccrine coil. Findings typical of bacterial cellulitis are lacking. Lymphocytic vasculitis may relate to a vasculopathic hypersensitivity reaction (e.g. due to a drug) or connective tissue disease. Clinical correlation required.	Inflamed control	0.13
002	Cellulitis	-	-	-	Superficial perivascular lymphocytic infiltrate with associated dermal edema and rare eosinophils: Gram stain negative (such findings, although non-specific, may be seen in association with a predominantly dermal delayed hypersensitivity reaction). Clinical correlation is required.	Inflamed control	undetectable
018	Cellulitis	2 days	-	-	Superficial dermal perivascular lymphocytic infiltrate with rare eosinophils and neutrophils consistent with mild hypersensitivity reaction (possibly mixed type IV and I); Gram stain negative.	Inflamed control	0.10
020	Dermatitis	-	-	-	Superficial and mid-dermal perivascular lymphocytic infiltrate with occasional eosinophils consistent with delayed hypersensitivity reaction; Gram stain negative.	Inflamed control	undetectable
021	Dermatitis	-	-	-	Dermal edema, superficial and deep, with sparse associated perivascular lymphoid component (non-specific). Gram stain negative.	Inflamed control	undetectable
026	Dermatitis	-	-	-	Fat only (no additional tissue in block). Gram stain negative.	Inflamed control	undetectable
031	Dermatitis	-	-	-	Superficial perivascular lymphocytic infiltrate with aggregated neutrophils in scale, most consistent with delayed hypersensitivity reaction, possibly impetiginized; Gram stain negative.	Inflamed control	undetectable
029	Dermatitis	-	coag-neg, non-hemolytic Staph	+	Superficial perivascular lymphocytic infiltrate most consistent with delayed hypersensitivity reaction; Gram stain negative.	Inflamed control	undetectable
007	Cellulitis	1 day	-	-	Superficial dermal edema and scattered superficial and deep dermal lymphocytes with rare admixed neutrophils. Gram stain negative (such findings are non-specific, although the possibility of a nearby or resolving area of more diagnostic cellulitis cannot be excluded).	Indeterminate	0.06
008	Cellulitis	3 days	-	-	Superficial and deep perivascular and interstitial mixed lymphocytic and neutrophilic infiltrate; Gram stain negative (the findings could indicate mild cellulitis; clinical correlation is required).	Indeterminate	0.06
009	Cellulitis	-	coag-neg, non-hemolytic Staph	-	Intralumenal neutrophils; consistent with urticarial immune response in appropriate clinical setting; Gram stain negative.	Indeterminate	undetectable
012	Cellulitis	<1 day	-	-	Minimal changes (no fat included); Gram stain negative.	Indeterminate	0.05
017	Cellulitis	-	-	-	Superficial dermal vascular prominence with basement membrane thickening (? stasis, age-related, diabetes, hypertension); Gram stain negative.	Indeterminate	undetectable
022	Cellulitis	-	-	-	Superficial and deep perivascular mixed inflammatory infiltrate, neutrophil predominant, consistent with cellulitis in appropriate clinical setting. Gram stain: no definitive bacteria seen.	Indeterminate	0.37
023	Cellulitis	-	-	-	Superficial and deep sparse perivascular and interstitial mixed infiltrate approx. 50:50 neutrophils to lymphocytes);? Cellulitis; Gram stain- rare Gram positive (extracellular) of uncertain significance at tissue edge.	Indeterminate	undetectable
027	Cellulitis	-	-	-	Superficial and deep (incl. subcutis) mixed inflammatory infiltrate containing neutrophils, consistent with cellulitis; Gram stain negative.	Indeterminate	undetectable
028	Cellulitis	2 weeks (for another indication)	coag-neg, non-hemolytic Staph	-	Superficial and deep sparse perivascular lymphocytic infiltrate (non-specific); Gram stain negative. Note: this patient was diagnosed as having a cutaneous allergy to an antibiotic given for another indication.	Indeterminate	undetectable
019	Dermatitis	-	α-hemolytic strep, corynebacteria	-	Evolving lichen simplex chronicus with surface impetiginization	Indeterminate	undetectable
001	Normal volunteer	-	-		Sparse superficial perivascular lymphocytic infiltrate; Gram stain negative (potentially within normal limits)	Normal	undetectable
005	Normal volunteer	-	-	-	Within normal limits; Gram stain negative.	Normal	undetectable
006	Normal volunteer	-	-	-	Within normal limits; Gram stain negative.	Normal	undetectable
016	Normal volunteer	-	-	-	Within normal limits; Gram stain negative.	Normal	undetectable
030	Normal volunteer	-	Not collected	Within normal limits; Gram stain negative.	Normal	undetectable
032	Normal volunteer	-	-	-	Within normal limits; Gram stain negative.	Normal	undetectable
033	Normal volunteer	-	-	-	Within normal limits; Gram stain negative.	Normal	undetectable