This video presents two distinct dermatopathology cases involving deeply embedded plant material, highlighting the critical difference between foreign body reactions with "passenger fungi" and active fungal infections. The first case, a large wood splinter in a patient's hand, initially mimicking a soft tissue tumor, is shown to be surrounded by Splendora-Hoeppli phenomenon and non-invasive dematiaceous fungi (likely Alternaria) confined to the splinter. The second case, a thorn in an immunocompromised patient's finger, features similar fungal morphology but demonstrates the fungi actively invading surrounding tissue, signifying a true infection. Dr. Gardner emphasizes these distinctions for appropriate clinical management, recommending follow-up for non-invasive cases and considering active treatment for invasive infections.
Exploring Foreign Body Reactions and Fungal Infections in Dermatopathology
0:00 Dr. Jarrod Gardner conducts an online didactics session on infectious cases for pathology and dermatology residents.
A deep soft tissue mass on a patient's hand, initially suspected to be a tumor, was revealed to be a large wood splinter (a "whole branch").
0:49 Microscopic examination showed streaked artifacts (indicating a hard object), cellulose plant cell walls, and a prominent reactive halo identified as the Splendora-Hoeppli phenomenon (antigen-antibody complex deposition).
3:41 MRI confirmed the foreign body. The patient had no recollection of trauma, leading to humorous speculation about its origin.
4:52 Pigmented dematiaceous fungi (black molds, likely Alternaria) were observed within the wood splinter, described as "passenger fungi."
6:11 GMS and PAS stains highlighted the fungi and plant cell walls. The speaker stressed the inability to reliably speciate fungi from tissue sections alone.
7:11Key Takeaway: The fungi in this case were confined to the wood splinter and not invading the surrounding host tissue, indicating a reactive foreign body response rather than an active fungal infection. Management involved surgical removal of the splinter and patient follow-up, with systemic antifungals generally not required.
10:02 The speaker mentions Keiko QXP, a platform for pathologists to share scanned slides, where these cases are hosted.
10:33Case 2: Thorn in Finger (Active Fungal Infection)
A thorn embedded in the dermis of an immunocompromised patient's (leukemia) finger also showed fungi, morphologically similar to Alternaria.
10:59Key Takeaway: Crucially, the fungi in this case were actively growing out from the stick into the surrounding tissue, confirming a true fungal infection.
11:28 Despite negative cultures (possibly due to prior removal of the main lesion), this was considered an active infection warranting clinical intervention, though the patient ultimately did well.