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Gypsy moth caterpillar dermatitis—revisited
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Gypsy moth caterpillar dermatitis--revisited Virginia T. Allen, MD, O. Fred Miller III, MD, and William B. Tyler, M D
Danville, Pennsylvania Gypsy moth caterpillar dermatitis is a pruritie, papular, urticarial eruption on exposed skin that occurs most commonly after direct contact with the first instar larva of the gypsy moth (Lymantria dispar). We present two case reports to illustrate its clinical and histopathologic features. Both eases occurred during the spring of 1990 and coincided with the greatest infestation of L. disparin the Northeast to date. The pathogenesis of this distinctive gypsy moth dermatitis most likely involves histamine release by the caterpillar and a delayed hypersensitivity reaction in its host. (J AM ACAD DERMATOL1991;24:979-81.) Dermatitis from contact with members of the order Lepidoptera has been described since ancient Greek times. 1 Larvae of the brown-tailed moth (Euproctis chrysorrhoea) were reported to cause an urticarial reaction in humans in 1901. 2 Since its accidental introduction into Massachusetts in 1869, increasing infestations by the closely related gypsy moth (Lymantria dispar) have made it the most important defoliating insect of hardwood forests in the northeastern United States. 3 Although pruritic urticaria had been reported in laboratory personnel who were working with the gypsy moth caterpillar, it was not until the spring of 1981 that outbreaks of a distinctive pruritic dermatitis were reported in Connecticut, Massachusetts, Rhode Island, and Pennsylvania. Outbreaks coincided with the first instar larvae of the gypsy moths. Direct physical contact with caterpillars was found to be associated with the cutaneous eruption.1 Clinical findings included patchy erythema, erythematous papules, urticarial papules, and linear streaks on both exposed and nonexposed skin, with a predilection for the extremities. 4 Three theories for the pathogenesis of cutaneous lesions have been proposed: the intracutaneous injection of toxins by the gypsy moth via its setae (hollow appendages), a primary irritant reaction to insect hairs or appendages, and a hypersensitivity response to insect antigen. 1 During the spring of 1990, we observed six cases From Geisinger Medical Center. Accepted for publication Jan. 28, 1991. Reprint requests: VirginiaT. Allen, MD, Department of Dermatology, Geisinger Medical Center, Danville, PA 17822. 16/1/28269
of gypsy moth caterpillar derhaatitis. Two representative cases illustrate the common clinical and histopathologic changes. CASE REPORTS Case 1
A 58-year-old white road inspector had a pruritie eruption of his neck and shoulders for 3 days. He also complained of nasal congestion, sneezing, and irritated eyes for 6 days. Four days earlier, several caterpillars had crawled on his neck. Physical examination revealed multiple, 1 to 5 mm, discrete and grouped, erythematous papulovesicles on the posterior and lateral apseets of the neck and shoulders. A shave biol~y specimen from the left shoulder showed focal spongiosis, mild epidermal hyperplasia, and a rather intense lymphohistiocytic infiltrate in a pedvascular distribution with a few admixed eosinophils (Fig. 1). The patient applied desoximetasone gel (Topieort) to the affected areas twice daily. All lesions cleared within 3 to 4 days. The upper respiratory symptoms also resolved uneventfully. Case 2 A 50-year-old white man had a 2-day history of prurifle "insect bites." Lesions had first appeared on the nape of his neck where he had brushed away gypsy moth caterpillars. One day before presentation, he had again encountered large numbers of airborne gypsy moth caterpillars while fishing. Physical examination revealed multiple, 2 to 8 mm, erythematous, urticarial papules on his flexor forearms, low back, and the posterior aspect of the neck. Lesions were found singly, in dusters, and linear groupings (Fig. 2). A biopsy specimen showed slight spongiosis and a perivascular lymphohistiocytic infiltrate that contained eosinophiis. 979
980
Journal of thc American Academy of Dermatology
Allen et al.
~.
....;i~84 j
d Fig. 1. Case 1. Focal slight spongiosis, mild epidermal hyperplasia, and perivascular lymphohistiocytic infiltrate with a few admixed eosinophils. (Hematoxylin-eosin stain; X25.) Fig. 2. Multiple single and linearly arranged urticarial papules on flexor forearms.
2ND INSTAR L A R V A (1ST WEEK
1ST I N S T A R L A R V A ( E A R L Y TO LATE M A Y )
I
EGG ( L A I D D U R I N G JULY AND AUGUST)
MOTH ( A D U L T - E M E R G E S AFTER 7 - 1 4 DAYS OF PUPATION)
~
PUPA ( C O C O O N OR R E S T I N G S T A G E - 3RD W E E K OF J U N E TO M I D - J U L Y ) 6 T H INSTAR L A R V A ( F E M A L E S O N L Y - 1ST WEEK 9 JULY)
OF JUNE)
3RD INSTAR L A R V A (2ND
WEEK
OF J U N E )
4TH INSTAR L A R V A ( 3 R D
WEEK
OF J U N E )
/
5TH INSTAR L A R V A ( 4 T H
WEEK
OF J U N E )
J
Fig. 3. Life cycle of the gypsy moth. Dermatitis generally is associated with first instar larva of the gypsy moth, which is highly mobile and airborne. (Data from Abrahamson L, Klass C. Gypsy moth. New York: Media Services at Cornell University, 1982:1-13.)
The patient was treated with an 8-day tapering course of oral prednisone and topical deseximetasone gel applied twice dairy to the affected areas with resolution within 1 week.
DISCUSSION During 1981, nearly 13 million forested acres were defoliated in the northeastern United States by
the gypsy moth. This number has already been surpassed by the massive infestation of L. di~par during the late spring and early summer of 1990. With successive defoliations, hardwood trees become stressed and die. This makes the gypsy moth caterpillar a serious ecologic threat. 3 Abrahamson and Klass 3 described the life cycle of the gypsy moth (Fig. 3). The female deposits her
Volume 24 Nttmher 6, Part 1 June 1991
eggs in a shady protected place during July and August. Larvae hatch in late April or early May during a 2- to 4-week period. In response to light, the caterpillars spin silken threads on which they "balloon" to the tops of trees, often becoming windborne in the process and spreading long distances. The developing larvae feed voraciously on the leaves of white oaks in the Northeast. Gypsy moth larvae develop by a series of molts and the stage between each molt is termed an instar. 3 Dermatitis generally is associated with the first instar larva, which is highly mobile and airborne. 1 The fifth and sixth instar larvae account for approximately 80% of all defoliation. Between the third week in June and mid-July, gypsy moth caterpillars attain their full larval size, cease feeding, and pupate in a protected location. Male moths emerge from pupation in 7 to 14 days followed by the females, mating occurs, and once the female has laid her eggs, both males and females die. Adult gypsy moths do not feed) Human exposure to gypsy moths can occur via direct contact with a caterpillar or with airborne insect hairs, silken threads, and shed skins. 6 Whether the pruritic cutaneous reaction that follows contact is secondary to mechanical irritation, the injection of vasoactive substances, or a hypersensitivity reaction remains unclear. Microscopic examination of the caterpillar reveals many tufts on its back that contain four soft and flexible hairs and 12 to 14 ball-and-socket lancets per tuft (Fig. 4). 7 With a radioenzyme assay, Shama et al. 4 demonstrated that whole first-stage larvae contain an average of 17.3 ng of histamine and the hairlike setae of the fifthstage larvae contain 80 ng of histamine per organism. Both mechanical irritation and histamine release by gypsy moth caterpillars and their setae may contribute to the urticarial response in humans. Evidence to suggest a hypersensitivity reaction is inconclusive. An epidemiologic study performed in a highly infested community in Massachusetts in 1982 showed that the one variable most strongly associated with acquiring a dermatitis was to have had a similar dermatitis during the previous spring infestation.6 Beaucher and Farnham 5 did closedpatch testing with gypsy moth caterpillar hairs and noted positive results in all patients with a history of gypsy moth caterpillar dermatitis but only one positive result in 11 control subjects. These results sug-
Gypsy moth dermatitis
,
981
"lk
Fig. 4. Portion of cross-section of gypsy moth caterpillar shows typical ball-and-socket lancet seta. (Hematoxylin-eosinstain; Xl00.) gest an immunologically mediated mechanism in sensitized persons similar to allergic contact dermatitisJ Both histamine release and a hypersensitivity reaction likely play a role and account for both an urticarial and a papulovesicular eruption in the same person. Each of the six patients in our study had a characteristic cutaneous reaction on exposed skin that ranged from erythematous papulovesicles to urticarial wheals within 24 hours of direct contact with gypsy moth caterpillars. Histopathologic findings included focal slight spongiosis and a perivascular lymphohistiocytic infiltrate with eosinophils. The findings are consistent with an urticarial allergic eruption and resemble an insect bite reaction. REFERENCES
1. Abcr R, Demdfi T, Gill T, et al. Rash illness associated with gypsy moth caterpillars--Pennsylvania. 1982;31:169-70. 2. White JC. Dermatitis produced by a caterpillar. Boston Med Surg J 1901;144:599. 3. Abrahamson L, Klass C. Gypsy moth. New York: Media Services at Cornell University, 1982:1-13. 4. Shama SK, Etkind PH, Odell TM, et al. Gypsy-moth-caterpillar dermatitis. N Eng[ J Med 1982;306:1300-1. 5. Beaucher WN, Farnham JE. Gypsy-moth-caterpillar dermatitis. N Engl J Med 1982;306:1301-2. 6. Tuthill KW, Canada AT, WilcockK, et al. An epidemiologic study of gypsy moth rash. Am J Public Health 1984;74:799803. 7. Berman BA, Ross RN. Gypsy moth caterpillar dermatitis. Cutis 1983;31:251,258. 8. Etkind PH, Odell TM, Canada AT, et al. The gypsy moth caterpillar: a significant new occupational and public health problem. J Occup Med 1982;24:659-62.
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I
Gypsy moth caterpillar dermatitis--revisited Virginia T. Allen, MD, O. Fred Miller III, MD, and William B. Tyler, M D
Danville, Pennsylvania Gypsy moth caterpillar dermatitis is a pruritie, papular, urticarial eruption on exposed skin that occurs most commonly after direct contact with the first instar larva of the gypsy moth (Lymantria dispar). We present two case reports to illustrate its clinical and histopathologic features. Both eases occurred during the spring of 1990 and coincided with the greatest infestation of L. disparin the Northeast to date. The pathogenesis of this distinctive gypsy moth dermatitis most likely involves histamine release by the caterpillar and a delayed hypersensitivity reaction in its host. (J AM ACAD DERMATOL1991;24:979-81.) Dermatitis from contact with members of the order Lepidoptera has been described since ancient Greek times. 1 Larvae of the brown-tailed moth (Euproctis chrysorrhoea) were reported to cause an urticarial reaction in humans in 1901. 2 Since its accidental introduction into Massachusetts in 1869, increasing infestations by the closely related gypsy moth (Lymantria dispar) have made it the most important defoliating insect of hardwood forests in the northeastern United States. 3 Although pruritic urticaria had been reported in laboratory personnel who were working with the gypsy moth caterpillar, it was not until the spring of 1981 that outbreaks of a distinctive pruritic dermatitis were reported in Connecticut, Massachusetts, Rhode Island, and Pennsylvania. Outbreaks coincided with the first instar larvae of the gypsy moths. Direct physical contact with caterpillars was found to be associated with the cutaneous eruption.1 Clinical findings included patchy erythema, erythematous papules, urticarial papules, and linear streaks on both exposed and nonexposed skin, with a predilection for the extremities. 4 Three theories for the pathogenesis of cutaneous lesions have been proposed: the intracutaneous injection of toxins by the gypsy moth via its setae (hollow appendages), a primary irritant reaction to insect hairs or appendages, and a hypersensitivity response to insect antigen. 1 During the spring of 1990, we observed six cases From Geisinger Medical Center. Accepted for publication Jan. 28, 1991. Reprint requests: VirginiaT. Allen, MD, Department of Dermatology, Geisinger Medical Center, Danville, PA 17822. 16/1/28269
of gypsy moth caterpillar derhaatitis. Two representative cases illustrate the common clinical and histopathologic changes. CASE REPORTS Case 1
A 58-year-old white road inspector had a pruritie eruption of his neck and shoulders for 3 days. He also complained of nasal congestion, sneezing, and irritated eyes for 6 days. Four days earlier, several caterpillars had crawled on his neck. Physical examination revealed multiple, 1 to 5 mm, discrete and grouped, erythematous papulovesicles on the posterior and lateral apseets of the neck and shoulders. A shave biol~y specimen from the left shoulder showed focal spongiosis, mild epidermal hyperplasia, and a rather intense lymphohistiocytic infiltrate in a pedvascular distribution with a few admixed eosinophils (Fig. 1). The patient applied desoximetasone gel (Topieort) to the affected areas twice daily. All lesions cleared within 3 to 4 days. The upper respiratory symptoms also resolved uneventfully. Case 2 A 50-year-old white man had a 2-day history of prurifle "insect bites." Lesions had first appeared on the nape of his neck where he had brushed away gypsy moth caterpillars. One day before presentation, he had again encountered large numbers of airborne gypsy moth caterpillars while fishing. Physical examination revealed multiple, 2 to 8 mm, erythematous, urticarial papules on his flexor forearms, low back, and the posterior aspect of the neck. Lesions were found singly, in dusters, and linear groupings (Fig. 2). A biopsy specimen showed slight spongiosis and a perivascular lymphohistiocytic infiltrate that contained eosinophiis. 979
980
Journal of thc American Academy of Dermatology
Allen et al.
~.
....;i~84 j
d Fig. 1. Case 1. Focal slight spongiosis, mild epidermal hyperplasia, and perivascular lymphohistiocytic infiltrate with a few admixed eosinophils. (Hematoxylin-eosin stain; X25.) Fig. 2. Multiple single and linearly arranged urticarial papules on flexor forearms.
2ND INSTAR L A R V A (1ST WEEK
1ST I N S T A R L A R V A ( E A R L Y TO LATE M A Y )
I
EGG ( L A I D D U R I N G JULY AND AUGUST)
MOTH ( A D U L T - E M E R G E S AFTER 7 - 1 4 DAYS OF PUPATION)
~
PUPA ( C O C O O N OR R E S T I N G S T A G E - 3RD W E E K OF J U N E TO M I D - J U L Y ) 6 T H INSTAR L A R V A ( F E M A L E S O N L Y - 1ST WEEK 9 JULY)
OF JUNE)
3RD INSTAR L A R V A (2ND
WEEK
OF J U N E )
4TH INSTAR L A R V A ( 3 R D
WEEK
OF J U N E )
/
5TH INSTAR L A R V A ( 4 T H
WEEK
OF J U N E )
J
Fig. 3. Life cycle of the gypsy moth. Dermatitis generally is associated with first instar larva of the gypsy moth, which is highly mobile and airborne. (Data from Abrahamson L, Klass C. Gypsy moth. New York: Media Services at Cornell University, 1982:1-13.)
The patient was treated with an 8-day tapering course of oral prednisone and topical deseximetasone gel applied twice dairy to the affected areas with resolution within 1 week.
DISCUSSION During 1981, nearly 13 million forested acres were defoliated in the northeastern United States by
the gypsy moth. This number has already been surpassed by the massive infestation of L. di~par during the late spring and early summer of 1990. With successive defoliations, hardwood trees become stressed and die. This makes the gypsy moth caterpillar a serious ecologic threat. 3 Abrahamson and Klass 3 described the life cycle of the gypsy moth (Fig. 3). The female deposits her
Volume 24 Nttmher 6, Part 1 June 1991
eggs in a shady protected place during July and August. Larvae hatch in late April or early May during a 2- to 4-week period. In response to light, the caterpillars spin silken threads on which they "balloon" to the tops of trees, often becoming windborne in the process and spreading long distances. The developing larvae feed voraciously on the leaves of white oaks in the Northeast. Gypsy moth larvae develop by a series of molts and the stage between each molt is termed an instar. 3 Dermatitis generally is associated with the first instar larva, which is highly mobile and airborne. 1 The fifth and sixth instar larvae account for approximately 80% of all defoliation. Between the third week in June and mid-July, gypsy moth caterpillars attain their full larval size, cease feeding, and pupate in a protected location. Male moths emerge from pupation in 7 to 14 days followed by the females, mating occurs, and once the female has laid her eggs, both males and females die. Adult gypsy moths do not feed) Human exposure to gypsy moths can occur via direct contact with a caterpillar or with airborne insect hairs, silken threads, and shed skins. 6 Whether the pruritic cutaneous reaction that follows contact is secondary to mechanical irritation, the injection of vasoactive substances, or a hypersensitivity reaction remains unclear. Microscopic examination of the caterpillar reveals many tufts on its back that contain four soft and flexible hairs and 12 to 14 ball-and-socket lancets per tuft (Fig. 4). 7 With a radioenzyme assay, Shama et al. 4 demonstrated that whole first-stage larvae contain an average of 17.3 ng of histamine and the hairlike setae of the fifthstage larvae contain 80 ng of histamine per organism. Both mechanical irritation and histamine release by gypsy moth caterpillars and their setae may contribute to the urticarial response in humans. Evidence to suggest a hypersensitivity reaction is inconclusive. An epidemiologic study performed in a highly infested community in Massachusetts in 1982 showed that the one variable most strongly associated with acquiring a dermatitis was to have had a similar dermatitis during the previous spring infestation.6 Beaucher and Farnham 5 did closedpatch testing with gypsy moth caterpillar hairs and noted positive results in all patients with a history of gypsy moth caterpillar dermatitis but only one positive result in 11 control subjects. These results sug-
Gypsy moth dermatitis
,
981
"lk
Fig. 4. Portion of cross-section of gypsy moth caterpillar shows typical ball-and-socket lancet seta. (Hematoxylin-eosinstain; Xl00.) gest an immunologically mediated mechanism in sensitized persons similar to allergic contact dermatitisJ Both histamine release and a hypersensitivity reaction likely play a role and account for both an urticarial and a papulovesicular eruption in the same person. Each of the six patients in our study had a characteristic cutaneous reaction on exposed skin that ranged from erythematous papulovesicles to urticarial wheals within 24 hours of direct contact with gypsy moth caterpillars. Histopathologic findings included focal slight spongiosis and a perivascular lymphohistiocytic infiltrate with eosinophils. The findings are consistent with an urticarial allergic eruption and resemble an insect bite reaction. REFERENCES
1. Abcr R, Demdfi T, Gill T, et al. Rash illness associated with gypsy moth caterpillars--Pennsylvania. 1982;31:169-70. 2. White JC. Dermatitis produced by a caterpillar. Boston Med Surg J 1901;144:599. 3. Abrahamson L, Klass C. Gypsy moth. New York: Media Services at Cornell University, 1982:1-13. 4. Shama SK, Etkind PH, Odell TM, et al. Gypsy-moth-caterpillar dermatitis. N Eng[ J Med 1982;306:1300-1. 5. Beaucher WN, Farnham JE. Gypsy-moth-caterpillar dermatitis. N Engl J Med 1982;306:1301-2. 6. Tuthill KW, Canada AT, WilcockK, et al. An epidemiologic study of gypsy moth rash. Am J Public Health 1984;74:799803. 7. Berman BA, Ross RN. Gypsy moth caterpillar dermatitis. Cutis 1983;31:251,258. 8. Etkind PH, Odell TM, Canada AT, et al. The gypsy moth caterpillar: a significant new occupational and public health problem. J Occup Med 1982;24:659-62.