Richard H. Flowers, MD

THE DIAGNOSIS: Vegetative Majocchi Granuloma

A biopsy and tissue culture showed acute dermal inflammation with granulomatous features and numerous fungal hyphae within the stratum corneum (Figure 1A), which were confirmed on GrocottGomori methenamine-silver staining (Figure 1B). Gram and Fite stains were negative for bacteria. A tissue culture speciated Trichophyton rubrum, which led to a diagnosis of deep dermatophyte infection (Majocchi granuloma) with a highly unusual clinical presentation of vegetative plaques. Predisposing factors included treatment with topical corticosteroids and possibly poor health and nutritional status at baseline. Our patient was treated with fluconazole 200 mg daily for 6 weeks, with near resolution of lesions at 3-week follow-up (Figure 2).

Dermatophytes are a common cause of superficial skin infections. The classic morphology consists of an annular scaly plaque; however, a wide variety of presentations have been observed (eg, verrucous, vesicular, pustular, granulomatous). Therefore, dermatophyte infections often mimic other dermatologic conditions, including atopic dermatitis, rosacea, psoriasis, bacterial abscess, erythema gyratum repens, lupus, granuloma annulare, cutaneous lymphoma, Hailey-Hailey disease, scarring alopecia, and syphilis.¹

Notably, when dermatophytes grow downward along hair follicles causing deeper infection, disruption of the follicular wall can lead to an excessive inflammatory response with granulomatous features.² Risk factors include cutaneous trauma, long-standing infection, immunocompromise, and treatment with topical corticosteroids.³ This disease evolution clinically appears as a nodule or infiltrated plaque, often without scale. The most well-known example is a kerion on the scalp. Elsewhere on the body, lesions often are termed Majocchi granulomas.²

Vegetative plaques, as seen in our patient, are a highly unusual morphology for deep tinea infection. Guanziroli et al⁴ reported a case of vegetative lesions on the forearm of a 67-year-old immunocompromised man that were successfully treated with a 3-month course of oral terbinafine after Trichophyton verrucosum was isolated. Skorepova et al⁵ reported a case of pyoderma vegetans triggered by recurrent Trichophyton mentagrophytes on the dorsal hands of a 64-year-old man with immunoglobulin deficiency of unknown etiology. The lesions were successfully treated with a prolonged course of doxycycline, topical triamcinolone, and intravenous immunoglobulin following 2 initial courses of terbinafine.

The differential diagnosis for vegetative lesions includes pemphigus vegetans, a vegetative variant of pyoderma gangrenosum; halogenoderma; and a variety of infections, including dimorphic fungi (histoplasmosis, blastomycosis), blastomycosislike pyoderma (bacterial), and candidiasis.⁶ These conditions usually can be distinguished based on histopathology. Clinically, pemphigus vegetans presents with pustules and vegetative lesions, as in our patient, but usually is more diffuse and favors the intertriginous areas. Histology likely would reveal foci of acantholysis and eosinophils. Vegetative pyoderma gangrenosum favors the trunk, particularly in sites of surgical trauma. In our patient, no lesions were present near the abdominal surgical sites, and there was no antecedent cribriform ulceration. Halogenoderma was a strong initial consideration given the localization, presence of large pustules, and history of numerous contrast computed tomography studies; however, our patient’s iodine levels were normal. Infectious etiologies including dimorphic fungi and blastomycosislike pyoderma generally are not restricted to the head and neck, and tissue culture helps exclude them. Vegetative lesions may occur in the setting of other infections, and tissue culture may be necessary to differentiate them if histopathology is not suggestive.

Deep dermatophyte infections require treatment with oral antifungals, as topicals do not penetrate adequately into the hair follicles. Exact regimens vary, but generally oral terbinafine or an oral azole (except ketoconazole) is administered for 2 to 6 weeks, with immunocompromise necessitating longer courses.

We present a rare case of vegetative Majocchi granuloma secondary to T rubrum infection. A dermatophyte infection should be included in the differential for vegetative lesions, especially in dense hair-bearing areas such as the beard. Treatment generally is straightforward with oral antifungals.

THE DIAGNOSIS: Vegetative Majocchi Granuloma

A biopsy and tissue culture showed acute dermal inflammation with granulomatous features and numerous fungal hyphae within the stratum corneum (Figure 1A), which were confirmed on GrocottGomori methenamine-silver staining (Figure 1B). Gram and Fite stains were negative for bacteria. A tissue culture speciated Trichophyton rubrum, which led to a diagnosis of deep dermatophyte infection (Majocchi granuloma) with a highly unusual clinical presentation of vegetative plaques. Predisposing factors included treatment with topical corticosteroids and possibly poor health and nutritional status at baseline. Our patient was treated with fluconazole 200 mg daily for 6 weeks, with near resolution of lesions at 3-week follow-up (Figure 2).

Dermatophytes are a common cause of superficial skin infections. The classic morphology consists of an annular scaly plaque; however, a wide variety of presentations have been observed (eg, verrucous, vesicular, pustular, granulomatous). Therefore, dermatophyte infections often mimic other dermatologic conditions, including atopic dermatitis, rosacea, psoriasis, bacterial abscess, erythema gyratum repens, lupus, granuloma annulare, cutaneous lymphoma, Hailey-Hailey disease, scarring alopecia, and syphilis.¹

Notably, when dermatophytes grow downward along hair follicles causing deeper infection, disruption of the follicular wall can lead to an excessive inflammatory response with granulomatous features.² Risk factors include cutaneous trauma, long-standing infection, immunocompromise, and treatment with topical corticosteroids.³ This disease evolution clinically appears as a nodule or infiltrated plaque, often without scale. The most well-known example is a kerion on the scalp. Elsewhere on the body, lesions often are termed Majocchi granulomas.²

Vegetative plaques, as seen in our patient, are a highly unusual morphology for deep tinea infection. Guanziroli et al⁴ reported a case of vegetative lesions on the forearm of a 67-year-old immunocompromised man that were successfully treated with a 3-month course of oral terbinafine after Trichophyton verrucosum was isolated. Skorepova et al⁵ reported a case of pyoderma vegetans triggered by recurrent Trichophyton mentagrophytes on the dorsal hands of a 64-year-old man with immunoglobulin deficiency of unknown etiology. The lesions were successfully treated with a prolonged course of doxycycline, topical triamcinolone, and intravenous immunoglobulin following 2 initial courses of terbinafine.

The differential diagnosis for vegetative lesions includes pemphigus vegetans, a vegetative variant of pyoderma gangrenosum; halogenoderma; and a variety of infections, including dimorphic fungi (histoplasmosis, blastomycosis), blastomycosislike pyoderma (bacterial), and candidiasis.⁶ These conditions usually can be distinguished based on histopathology. Clinically, pemphigus vegetans presents with pustules and vegetative lesions, as in our patient, but usually is more diffuse and favors the intertriginous areas. Histology likely would reveal foci of acantholysis and eosinophils. Vegetative pyoderma gangrenosum favors the trunk, particularly in sites of surgical trauma. In our patient, no lesions were present near the abdominal surgical sites, and there was no antecedent cribriform ulceration. Halogenoderma was a strong initial consideration given the localization, presence of large pustules, and history of numerous contrast computed tomography studies; however, our patient’s iodine levels were normal. Infectious etiologies including dimorphic fungi and blastomycosislike pyoderma generally are not restricted to the head and neck, and tissue culture helps exclude them. Vegetative lesions may occur in the setting of other infections, and tissue culture may be necessary to differentiate them if histopathology is not suggestive.

Deep dermatophyte infections require treatment with oral antifungals, as topicals do not penetrate adequately into the hair follicles. Exact regimens vary, but generally oral terbinafine or an oral azole (except ketoconazole) is administered for 2 to 6 weeks, with immunocompromise necessitating longer courses.

We present a rare case of vegetative Majocchi granuloma secondary to T rubrum infection. A dermatophyte infection should be included in the differential for vegetative lesions, especially in dense hair-bearing areas such as the beard. Treatment generally is straightforward with oral antifungals.

THE DIAGNOSIS: Vegetative Majocchi Granuloma

A biopsy and tissue culture showed acute dermal inflammation with granulomatous features and numerous fungal hyphae within the stratum corneum (Figure 1A), which were confirmed on GrocottGomori methenamine-silver staining (Figure 1B). Gram and Fite stains were negative for bacteria. A tissue culture speciated Trichophyton rubrum, which led to a diagnosis of deep dermatophyte infection (Majocchi granuloma) with a highly unusual clinical presentation of vegetative plaques. Predisposing factors included treatment with topical corticosteroids and possibly poor health and nutritional status at baseline. Our patient was treated with fluconazole 200 mg daily for 6 weeks, with near resolution of lesions at 3-week follow-up (Figure 2).

Dermatophytes are a common cause of superficial skin infections. The classic morphology consists of an annular scaly plaque; however, a wide variety of presentations have been observed (eg, verrucous, vesicular, pustular, granulomatous). Therefore, dermatophyte infections often mimic other dermatologic conditions, including atopic dermatitis, rosacea, psoriasis, bacterial abscess, erythema gyratum repens, lupus, granuloma annulare, cutaneous lymphoma, Hailey-Hailey disease, scarring alopecia, and syphilis.¹

Notably, when dermatophytes grow downward along hair follicles causing deeper infection, disruption of the follicular wall can lead to an excessive inflammatory response with granulomatous features.² Risk factors include cutaneous trauma, long-standing infection, immunocompromise, and treatment with topical corticosteroids.³ This disease evolution clinically appears as a nodule or infiltrated plaque, often without scale. The most well-known example is a kerion on the scalp. Elsewhere on the body, lesions often are termed Majocchi granulomas.²

Vegetative plaques, as seen in our patient, are a highly unusual morphology for deep tinea infection. Guanziroli et al⁴ reported a case of vegetative lesions on the forearm of a 67-year-old immunocompromised man that were successfully treated with a 3-month course of oral terbinafine after Trichophyton verrucosum was isolated. Skorepova et al⁵ reported a case of pyoderma vegetans triggered by recurrent Trichophyton mentagrophytes on the dorsal hands of a 64-year-old man with immunoglobulin deficiency of unknown etiology. The lesions were successfully treated with a prolonged course of doxycycline, topical triamcinolone, and intravenous immunoglobulin following 2 initial courses of terbinafine.

The differential diagnosis for vegetative lesions includes pemphigus vegetans, a vegetative variant of pyoderma gangrenosum; halogenoderma; and a variety of infections, including dimorphic fungi (histoplasmosis, blastomycosis), blastomycosislike pyoderma (bacterial), and candidiasis.⁶ These conditions usually can be distinguished based on histopathology. Clinically, pemphigus vegetans presents with pustules and vegetative lesions, as in our patient, but usually is more diffuse and favors the intertriginous areas. Histology likely would reveal foci of acantholysis and eosinophils. Vegetative pyoderma gangrenosum favors the trunk, particularly in sites of surgical trauma. In our patient, no lesions were present near the abdominal surgical sites, and there was no antecedent cribriform ulceration. Halogenoderma was a strong initial consideration given the localization, presence of large pustules, and history of numerous contrast computed tomography studies; however, our patient’s iodine levels were normal. Infectious etiologies including dimorphic fungi and blastomycosislike pyoderma generally are not restricted to the head and neck, and tissue culture helps exclude them. Vegetative lesions may occur in the setting of other infections, and tissue culture may be necessary to differentiate them if histopathology is not suggestive.

Deep dermatophyte infections require treatment with oral antifungals, as topicals do not penetrate adequately into the hair follicles. Exact regimens vary, but generally oral terbinafine or an oral azole (except ketoconazole) is administered for 2 to 6 weeks, with immunocompromise necessitating longer courses.

We present a rare case of vegetative Majocchi granuloma secondary to T rubrum infection. A dermatophyte infection should be included in the differential for vegetative lesions, especially in dense hair-bearing areas such as the beard. Treatment generally is straightforward with oral antifungals.

Case Reports

Patient 1
A 65-year-old woman presented to the dermatology clinic in July with a pruritic rash of 2 days’ duration that started on the back and spread diffusely. The patient gardened regularly. Physical examination showed inflammatory papules and pustules on the back (Figure 1), as well as the groin, breasts, and ears. There was a punctate black dot in the center of some papules, and dermoscopy revealed ticks (Figure 2). Removal and microscopic examination confirmed larval-stage lone star ticks (Figure 3). The patient was prescribed topical steroids for pruritus as well as oral doxycycline for prophylaxis against tick-borne illnesses.

Patient 2
A 54-year-old man presented to the same clinic in July with pruritic lesions on the back, legs, ankles, and scrotum of 3 days’ duration that first appeared 24 hours after performing yardwork. Physical examination revealed diffusely distributed papules, pustules, and vesicles on the back (Figure 4). Some papules featured a punctate black dot in the center (similar to patient 1), and dermoscopy again revealed ticks. Removal and microscopic examination confirmed larval-stage ticks. The patient was treated with topical steroids and oral antihistamines for pruritus as well as prophylactic oral doxycycline.

Comment

Ticks are well-known human parasites, representing the second most common vector of human infectious disease.¹ Ticks have 3 motile stages: larva (or “seed”), nymph, and adult. They can bite humans during all stages. Larval ticks, distinguished by having 6 legs rather than 8 legs in nymphs and adults, can attack in droves and cause an infestation that presents as diffuse, pruritic, erythematous papules and pustules.^2-4 The first report of larval tick infestation in humans may have been in 1728 by William Byrd who described finding ticks on the skin that were too small to see without a microscope.⁵

Identification
The ticks in both of our cases were lone star ticks (Amblyomma americanum). The larval stage of A americanum is a proven cause of cutaneous reaction.^6,7 A PubMed search of articles indexed for MEDLINE as well as a Google Scholar search using the terms tick, seed tick, or tick bite in combination with rash, eruption, infestation, papule, pustule, or pruritic revealed 6 reported cases of larval tick infestation in the literature (including our case); 5 were caused by A americanum and 1 by Ixodes dammini (now known as Ixodes scapularis); all occurred in July or August.^3,7-10 This time frame is consistent with the general tick life cycle across species: Adults feed from April to June, then lay eggs that hatch into larval ticks within 4 to 6 weeks. After hatching, larval ticks climb grass and weeds awaiting a passing host.⁴

Diagnosis
Larval tick infestation remains a frequently misdiagnosed etiology of diffuse pruritic papules and pustules, especially in urban settings where physicians are less likely to be familiar with this type of manifestation.^3,9-11 Larval ticks are submillimeter in size and difficult to appreciate with the naked eye, contributing to misdiagnosis. A punctate black dot may sometimes be seen in papules; however, dermoscopy is critical for accurate diagnosis, as hemorrhagic crust is a frequent misdiagnosis.

Management
In addition to symptomatic therapy, both of our patients received doxycycline as antibiotic prophylaxis for tick-borne illnesses given that a high number of ticks had been attached for more than 2 days.^12,13 Antibiotic prophylaxis for tick-borne illness is controversial. The exception is Lyme disease transmitted by nymphal or adult I scapularis when specific conditions are met: the bite must have occurred in an endemic area, doxycycline cannot be contraindicated, estimated duration of attachment is at least 36 hours, and prophylaxis must be started within 72 hours of tick removal.¹³ There are no official recommendations for the A americanum species or for larval-stage ticks of any species. Larval-stage ticks acting as vectors for disease transmission is not well documented in recent literature, and there currently is limited evidence supporting prophylactic antibiotics for larval tick bites. The presence of spotted fever rickettsioses has been reported (with the exception of Rickettsia rickettsii and Ehrlichia chaffeensis) in larval A americanum ticks, suggesting a theoretical possibility that they could act as disease vectors.^3,8,11,14-17 At a minimum, both prompt tick removal and close patient follow-up is warranted.

Conclusion

Human infestation with larval ticks is a common occurrence but can present a diagnostic challenge to an unfamiliar physician. We encourage consideration of larval tick infestation as the etiology of multiple or diffuse pruritic papules with a history of outdoor exposure.

Case Reports

Patient 1
A 65-year-old woman presented to the dermatology clinic in July with a pruritic rash of 2 days’ duration that started on the back and spread diffusely. The patient gardened regularly. Physical examination showed inflammatory papules and pustules on the back (Figure 1), as well as the groin, breasts, and ears. There was a punctate black dot in the center of some papules, and dermoscopy revealed ticks (Figure 2). Removal and microscopic examination confirmed larval-stage lone star ticks (Figure 3). The patient was prescribed topical steroids for pruritus as well as oral doxycycline for prophylaxis against tick-borne illnesses.

Patient 2
A 54-year-old man presented to the same clinic in July with pruritic lesions on the back, legs, ankles, and scrotum of 3 days’ duration that first appeared 24 hours after performing yardwork. Physical examination revealed diffusely distributed papules, pustules, and vesicles on the back (Figure 4). Some papules featured a punctate black dot in the center (similar to patient 1), and dermoscopy again revealed ticks. Removal and microscopic examination confirmed larval-stage ticks. The patient was treated with topical steroids and oral antihistamines for pruritus as well as prophylactic oral doxycycline.

Comment

Ticks are well-known human parasites, representing the second most common vector of human infectious disease.¹ Ticks have 3 motile stages: larva (or “seed”), nymph, and adult. They can bite humans during all stages. Larval ticks, distinguished by having 6 legs rather than 8 legs in nymphs and adults, can attack in droves and cause an infestation that presents as diffuse, pruritic, erythematous papules and pustules.^2-4 The first report of larval tick infestation in humans may have been in 1728 by William Byrd who described finding ticks on the skin that were too small to see without a microscope.⁵

Identification
The ticks in both of our cases were lone star ticks (Amblyomma americanum). The larval stage of A americanum is a proven cause of cutaneous reaction.^6,7 A PubMed search of articles indexed for MEDLINE as well as a Google Scholar search using the terms tick, seed tick, or tick bite in combination with rash, eruption, infestation, papule, pustule, or pruritic revealed 6 reported cases of larval tick infestation in the literature (including our case); 5 were caused by A americanum and 1 by Ixodes dammini (now known as Ixodes scapularis); all occurred in July or August.^3,7-10 This time frame is consistent with the general tick life cycle across species: Adults feed from April to June, then lay eggs that hatch into larval ticks within 4 to 6 weeks. After hatching, larval ticks climb grass and weeds awaiting a passing host.⁴

Diagnosis
Larval tick infestation remains a frequently misdiagnosed etiology of diffuse pruritic papules and pustules, especially in urban settings where physicians are less likely to be familiar with this type of manifestation.^3,9-11 Larval ticks are submillimeter in size and difficult to appreciate with the naked eye, contributing to misdiagnosis. A punctate black dot may sometimes be seen in papules; however, dermoscopy is critical for accurate diagnosis, as hemorrhagic crust is a frequent misdiagnosis.

Management
In addition to symptomatic therapy, both of our patients received doxycycline as antibiotic prophylaxis for tick-borne illnesses given that a high number of ticks had been attached for more than 2 days.^12,13 Antibiotic prophylaxis for tick-borne illness is controversial. The exception is Lyme disease transmitted by nymphal or adult I scapularis when specific conditions are met: the bite must have occurred in an endemic area, doxycycline cannot be contraindicated, estimated duration of attachment is at least 36 hours, and prophylaxis must be started within 72 hours of tick removal.¹³ There are no official recommendations for the A americanum species or for larval-stage ticks of any species. Larval-stage ticks acting as vectors for disease transmission is not well documented in recent literature, and there currently is limited evidence supporting prophylactic antibiotics for larval tick bites. The presence of spotted fever rickettsioses has been reported (with the exception of Rickettsia rickettsii and Ehrlichia chaffeensis) in larval A americanum ticks, suggesting a theoretical possibility that they could act as disease vectors.^3,8,11,14-17 At a minimum, both prompt tick removal and close patient follow-up is warranted.

Conclusion

Human infestation with larval ticks is a common occurrence but can present a diagnostic challenge to an unfamiliar physician. We encourage consideration of larval tick infestation as the etiology of multiple or diffuse pruritic papules with a history of outdoor exposure.

Case Reports

Patient 1
A 65-year-old woman presented to the dermatology clinic in July with a pruritic rash of 2 days’ duration that started on the back and spread diffusely. The patient gardened regularly. Physical examination showed inflammatory papules and pustules on the back (Figure 1), as well as the groin, breasts, and ears. There was a punctate black dot in the center of some papules, and dermoscopy revealed ticks (Figure 2). Removal and microscopic examination confirmed larval-stage lone star ticks (Figure 3). The patient was prescribed topical steroids for pruritus as well as oral doxycycline for prophylaxis against tick-borne illnesses.

Patient 2
A 54-year-old man presented to the same clinic in July with pruritic lesions on the back, legs, ankles, and scrotum of 3 days’ duration that first appeared 24 hours after performing yardwork. Physical examination revealed diffusely distributed papules, pustules, and vesicles on the back (Figure 4). Some papules featured a punctate black dot in the center (similar to patient 1), and dermoscopy again revealed ticks. Removal and microscopic examination confirmed larval-stage ticks. The patient was treated with topical steroids and oral antihistamines for pruritus as well as prophylactic oral doxycycline.

Comment

Ticks are well-known human parasites, representing the second most common vector of human infectious disease.¹ Ticks have 3 motile stages: larva (or “seed”), nymph, and adult. They can bite humans during all stages. Larval ticks, distinguished by having 6 legs rather than 8 legs in nymphs and adults, can attack in droves and cause an infestation that presents as diffuse, pruritic, erythematous papules and pustules.^2-4 The first report of larval tick infestation in humans may have been in 1728 by William Byrd who described finding ticks on the skin that were too small to see without a microscope.⁵

Identification
The ticks in both of our cases were lone star ticks (Amblyomma americanum). The larval stage of A americanum is a proven cause of cutaneous reaction.^6,7 A PubMed search of articles indexed for MEDLINE as well as a Google Scholar search using the terms tick, seed tick, or tick bite in combination with rash, eruption, infestation, papule, pustule, or pruritic revealed 6 reported cases of larval tick infestation in the literature (including our case); 5 were caused by A americanum and 1 by Ixodes dammini (now known as Ixodes scapularis); all occurred in July or August.^3,7-10 This time frame is consistent with the general tick life cycle across species: Adults feed from April to June, then lay eggs that hatch into larval ticks within 4 to 6 weeks. After hatching, larval ticks climb grass and weeds awaiting a passing host.⁴

Diagnosis
Larval tick infestation remains a frequently misdiagnosed etiology of diffuse pruritic papules and pustules, especially in urban settings where physicians are less likely to be familiar with this type of manifestation.^3,9-11 Larval ticks are submillimeter in size and difficult to appreciate with the naked eye, contributing to misdiagnosis. A punctate black dot may sometimes be seen in papules; however, dermoscopy is critical for accurate diagnosis, as hemorrhagic crust is a frequent misdiagnosis.

Management
In addition to symptomatic therapy, both of our patients received doxycycline as antibiotic prophylaxis for tick-borne illnesses given that a high number of ticks had been attached for more than 2 days.^12,13 Antibiotic prophylaxis for tick-borne illness is controversial. The exception is Lyme disease transmitted by nymphal or adult I scapularis when specific conditions are met: the bite must have occurred in an endemic area, doxycycline cannot be contraindicated, estimated duration of attachment is at least 36 hours, and prophylaxis must be started within 72 hours of tick removal.¹³ There are no official recommendations for the A americanum species or for larval-stage ticks of any species. Larval-stage ticks acting as vectors for disease transmission is not well documented in recent literature, and there currently is limited evidence supporting prophylactic antibiotics for larval tick bites. The presence of spotted fever rickettsioses has been reported (with the exception of Rickettsia rickettsii and Ehrlichia chaffeensis) in larval A americanum ticks, suggesting a theoretical possibility that they could act as disease vectors.^3,8,11,14-17 At a minimum, both prompt tick removal and close patient follow-up is warranted.

Conclusion

Human infestation with larval ticks is a common occurrence but can present a diagnostic challenge to an unfamiliar physician. We encourage consideration of larval tick infestation as the etiology of multiple or diffuse pruritic papules with a history of outdoor exposure.