This video provides a detailed microscopic analysis of Hand-Foot-Mouth disease (HFMD) caused by coxsackievirus, examining two skin biopsy examples. The presenter identifies and explains the hallmark histopathological features, including rapid-onset "ballooning degeneration" of epidermal keratinocytes (characterized by pale, swollen, and enlarged cells with significant intracellular and intercellular edema or spongiosis). Accompanying dermal findings, such as papillary edema, perivascular hemorrhage, and mixed inflammation, are also highlighted, illustrating how these features collectively establish the diagnosis and aid in recognizing both classic and atypical clinical presentations.
Microscopic Diagnosis of Hand-Foot-Mouth Disease (Coxsackievirus)
0:00:06 Introduction to a Lesion: The video begins with a low-power microscopic view of a skin lesion, inviting viewers to identify its pathology.
0:00:23 Epidermal Changes & Rapid Onset: The lesion shows dying keratinocytes, with the corneal layer remaining intact, indicating a rapid development of the pathology.
0:00:43 Key Histological Feature: Ballooning Degeneration: The primary epidermal characteristic is "ballooning degeneration," where keratinocytes appear pale, swollen, and enlarged due to intracellular fluid, accompanied by intercellular spongiosis (edema).
0:01:14 Dermal Manifestations: In the dermis, features include prominent papillary edema (pale, fluid-filled spaces with separated collagen fibers), along with perivascular hemorrhage and mixed inflammation around blood vessels.
0:01:32 Definitive Diagnosis: Hand-Foot-Mouth Disease (Coxsackievirus): The combination of these specific epidermal and dermal findings confirms the diagnosis of Hand-Foot-Mouth disease, typically caused by coxsackievirus.
0:01:40 Clinical Correlation & Atypical Presentations: The microscopic findings are linked to the clinical appearance (swollen erythema, pustular lesions). The presenter emphasizes that biopsies are often taken for cases with atypical clinical presentations.
0:02:12 Recognizing Subtle Clues: Even if full epidermal changes are not evident, the presence of hemorrhage and perivascular inflammation in papules on the hands and feet should raise suspicion for coxsackievirus, aiding in the diagnosis of unusual forms.
0:02:45 Second Illustrative Example: A second biopsy reinforces the characteristic features, showing an abrupt transition from normal skin to a swollen area with ballooning degeneration, an intact corneal layer, epidermal lifting by edema fluid, and dermal hemorrhage and edema.