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Case Reports

Abstract

Typically, perhaps in part due to Occam’s razor, a single diagnosis is made for one biopsy specimen. However, patients (and tissue sections) can be complex and fulfill Hickam’s dictum, possibly having multiple diagnoses. A male in his 60s with renal failure presented with bilateral hyperkeratotic plaques on the knees. A punch biopsy showed readily appreciable epidermal changes consistent with acquired perforating dermatosis (APD), including ulceration and vertically oriented collagen fibers. An increase in dermal/subcutaneous fibroblasts expanding adipose septa, suggestive of nephrogenic systemic fibrosis (NSF), was only noticed because the clinician who performed the biopsy later asked about NSF. We hypothesized that most biopsies have just one significant diagnosis. We searched PubMed and Medline for (“Occam’s Razor" OR “Hickam’s dictum” OR “multiple diagnoses”) AND “dermatopathology” for case series exploring multiple diagnoses in dermatopathology. Seventy-two studies were screened, and four were included. Two studies found multiple diagnoses in 73/583 (13%) of melanoma cases and 6/189 (3%) of female genital biopsies. One study found that in cases initially diagnosed as actinic keratosis, step levels identified additional diagnoses in 23/69 (33%) of cases. In a quality assurance study involving four cases with multiple diagnoses, correct diagnoses were made 58% of the time, compared to 77% in cases with a single diagnosis. Due to search satisficing and finding a “good enough” initial diagnosis, it can be easy to overlook additional histopathologic findings of significance. Awareness of this bias and data on when to be alert for multiple diagnoses can be helpful in daily practice.