Indian Journal of Dermatology
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Year : 2022  |  Volume : 67  |  Issue : 4  |  Page : 464-465
Cutaneous protothecosis

1 From the Department of Dermatology, Seth G.S. Medical College and KEM Hospital, Mumbai, Maharashtra, India
2 Department of Dermatology, VDGIMS (GMC), Latur, Maharashtra, India

Date of Web Publication2-Nov-2022

Correspondence Address:
Bhushan Darkase
Department of Dermatology, VDGIMS (GMC), Latur, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijd.ijd_127_21

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How to cite this article:
Mithari HS, Gole PV, Darkase B, Kalantri MS, Khopkar U. Cutaneous protothecosis. Indian J Dermatol 2022;67:464-5

How to cite this URL:
Mithari HS, Gole PV, Darkase B, Kalantri MS, Khopkar U. Cutaneous protothecosis. Indian J Dermatol [serial online] 2022 [cited 2023 Mar 31];67:464-5. Available from:


A 66-year-old fisherwoman presented to our outpatient department with red raised painful lesion over right hand and forearm associated with mild fever since 1 month. She had recurrent trauma while cleaning the fishes. On examination, well defined erythematous oedematous plaque, scarring and ulcers with yellow-white slough over extensor aspect of right forearm measuring 10 × 14 cm [Figure 1] and dusky erythematous plaque, white linear scars and punched out ulcers over the dorsum of right hand were seen [Figure 2]. General and systemic examination was normal. Differentials like cellulitis or deep mycosis like cryptococcosis, sporotrichosis were considered. Hematologic and biochemical laboratory findings were normal, except her blood sugar levels (HbA1c = 14%) suggestive of uncontrolled diabetes mellitus. The culture did not show any growth. Histopathological examination showed dermal suppurative granulomatous reaction consisting of lymphocytes, plasma cells, multinucleated giant cells, and multiple thick-walled spherical structures resembling yeast like cells were seen which, on higher magnification, showed internal septation and tightly packed endospores [Figure 3]. On periodic acid Schiff (PAS) staining, PAS-positive endospores were forming morula-like structure with cart-wheel like appearance, characteristic of Prototheca genus [Figure 4]. The patient was evaluated further for systemic involvement and any immunodeficiency. Flow cytometric analysis of peripheral blood had low absolute CD3, CD4 and CD8 T cell counts suggestive of decreased cell-mediated immunity of the patient. Thus, final diagnosis was cutaneous protothecosis.
Figure 1: Well defined erythematous oedematous plaque over extensor aspect of right forearm with scarring and ulcers covered with yellow-white slough

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Figure 2: Dusky erythematous plaque over the dorsum of right hand with white linear scars and punched out ulcers

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Figure 3: H&E stained histopathological image of plaque on forearm; at 4× magnification - suppurative granulomatous reaction in the dermis, at 100× magnification - multiple thick-walled spherical structures resembling yeast like cells with internal septations (red circle)

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Figure 4: Periodic acid Schiff (PAS) stained histopathological image at 100× magnification showing, PAS-positive endospores packed into sporangia (red circle) forming morula-like structure with cart-wheel like appearance (red arrow), characteristic of Prototheca genus

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The patient was treated with Amphotericin B 30 mg IV daily for 23 days followed by Capsule Itraconazole 200 mg BD for 2 months. The lesions healed with scarring after 2 weeks of starting treatment [Figure 5].
Figure 5: After 2 weeks of treatment with Amphotericin B, lesion on forearm healed with scarring

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Protothecosis is a rare infectious algal disease caused by Prototheca,[1] of which P. wickerhamii (more common) and P. zopfii are reported to cause human infections.[1] Protothecosis presents as (i) cutaneous lesions (most common), (ii) olecranon bursitis, and or (iii) disseminated systemic infections.[1] It usually affects immunocompromised patients though may occur in immunocompetent patient.[2] It occurs commonly on exposed sites as a vesiculobullous ulcerative lesion with crusting or as erythematous plaque, papules, nodules, verrucous lesion, usually associated with trauma or inoculation of the organism.[3] The differential diagnosis is deep mycosis like Coccidioidomycosis, Cryptococcosis, etc., which make biopsy and tissue culture necessary to identify the implicated organism. Diagnosis is based upon histopathologic examination of tissue demonstrating granulomatous inflammation with multiple sporangia having thick, double-layered walls filled with multiple endospores. Such sporangia are characteristic of the Prototheca spp. and tend to form morula-like structures having internal septation forming a cartwheel-like appearance.[1] The morula forms appear symmetrical in P. wickerhamii, whereas random internal segmentation is seen in other species.[1]

Culture of the organism is required for definitive diagnosis. Prototheca species have simple nutritional requirements. However, often a failure to isolate Prototheca (as was seen in our case) may be explained by the fact that commonly used culture media are unsatisfactory, contain unsuitable nutrients or inhibitors, e.g., cycloheximide, and also are readily overgrown by bacteria and fungi when culture is attempted.[1]

Disseminated infections are usually treated with Amphotericin B, whereas localised infections are treated with azoles like itraconazole or surgical excision.[4]

We report this case to emphasise the need to consider cutaneous protothecosis in a lesion that appears suspicious for the more-common fungal infections, especially in immunocompromised individuals.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Lass-Flörl C, Mayr A. Human protothecosis. Clin Microbiol Rev 2007;230-42.  Back to cited text no. 1
Kantrow SM, Boyd AS. Protothecosis. Dermatol Clin 2003;21:249-55.  Back to cited text no. 2
Chao SC, Hsu MM, Lee JY. Cutaneous protothecosis: Report of five cases. Br J Dermatol 2002;146:688-93.  Back to cited text no. 3
Mars PW, Rabhon AR, Rippey JJ, Ajello L. Cutaneous protothecosis. Br J Dermatol 1971;85:76-84.  Back to cited text no. 4


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]


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