Yonago Acta medica 2015;58:51–52

Patient Report

Tick Bite Granuloma: Recommendations for Surgical Treatment
Keisuke Hirota,* Yoshinaga Kurosawa,* Keisuke Goto, Koji Adachi, Yuichi Yoshida and Osamu Yamamoto
Division of Dermatology, Department of Medicine of Sensory and Motor Organs, School of Medicine, Tottori University Faculty ofMedicine, Yonago 683-8504, JapanABSTRACT
Tick bite is known as a possible cause of some infectious
diseases such as Lyme disease, spotted fever and related
illnesses. The reaction to a tick bite may persist for several months to several years and can sometimes cause
histopathological granuloma. The long-term reaction tosalivary extracts from the tick could be responsible fordevelopment of granuloma in our patient. We recommended complete resection as the only sure way to treat
formed granuloma.
Key words granuloma; histopathology; tick; treatment
Fig. 1. A red nodule with crusts on the right forehead.

Tick bite is known as a possible cause of Lyme disease
and spotted fever related illnesses.1 Sometimes it also
causes an immune reaction resulting in granuloma formation, even in the absence of parts of the tick’s mouthremaining in the skin.2 We report a case of tick bite
granuloma and discuss its pathogenesis and treatment.
PATIENT REPORT
A 3-year-old boy was referred to our clinic for evaluation of a red nodule on the right forehead. A tick on hisforehead had been removed by hand 5 months before.
Although he had been treated with topical steroid ointment for 2 months, the response was poor. Physical examination revealed a red nodule with crusts, 13 × 8 mmin diameter, on the right forehead (Fig. 1). His generalcondition was good and his personal past medical history was unremarkable. The lesion was excised underlocal anesthesia. Histopathological examination showed
focal parakeratosis, spongiosis and acanthosis in the epidermis (Fig. 2). In addition, there were mixed cell granulomas composed of lymphocytes, eosinophils, plasma
cells and histiocytes in the dermis (Fig. 3). Fragments ofthe tick were not involved in the resected tissue.

Fig. 2. Focal parakeratosis, spongiosis and acanthosis in the epidermis and granulomatous dermatitis (hematoxylin and eosin).
Bar = 500 µm.

DISCUSSION
Tick bite rarely causes granuloma. The progression oftissue reaction can be classified into three stages: acute,subacute and chronic phases.3 Predominant features in* Both authors contributed equally to this report.
Corresponding author: Yuichi Yoshida, MD
yxyhifu1@med.tottori-u.ac.jp
Received 2014 November 20
Accepted 2014 December 10Fig. 3. Mixed cell granulomas composed with lymphocytes, eosinophils and histiocytes are seen (hematoxylin and eosin). Bar =20 µm.

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the acute phase are dilation of superficial vessels, perivascular lymphocytic infiltrates, and intense epidermaland subepidermal infiltration of eosinophils. In thesubacute phase, diffuse edema and dense infiltration oflymphocytes, neutrophils, eosinophils and histiocytes
are seen, followed by an increase in fibrous tissue andthe sporadic burst of giant cells in the chronic phase.
The reaction to the bite of arthropods may persist forseveral months to several years. Stimulating agents of
the arthropod somehow persist actively in these lesions
for a remarkably long time. The history of an insect bite
may not be reported by the patient after a lapse of many
months. In such patients, it is possible for clinicians
to misdiagnose the lesion as a malignant lymphoma,
pyrexia Hodgkin’s granuloma or pseudolymphoma(lymphadenosis benigna cutis). In our patient, atypicallymphocytes or lymphoid follicles were not seen in thelesion.
Attempts to remove the living tick often result infragments of the tick being left in the skin. It has been
speculated that the reaction to the fragments of the tickis related to the pathogenesis of granuloma.4 On theother hand, the long-term reaction to the salivary extracts from a tick can be responsible for developmentof the lesion. It has been reported that frequent biopsies
contributed to the eventual disappearance of tick bite
granuloma.5 In our patient, no fragments of the tick were
found in the resected lesion. Therefore, salivary extracts
might be related to the granuloma in our patient.

To our knowledge, there are few reports of treatment
for tick bite granuloma. Treatment with topical steroid
ointment was not effective at all in our patient. Although
topical injection of corticosteroids to the granuloma canbe used for treatment, it is likely that the effect wouldappear only temporally if the remaining fragments havenot been removed. Oral administration of corticosteroid
is less recommended due to its systemic side effects,
particularly in children. Accordingly, we recommend
complete resection as the only way for treating formed
granuloma regardless of whether tick fragments remained or not since it is assumed that it takes a longtime for spontaneous regression.
Owing to these facts, in unusual cases in which dermatitis follows a tick bite, excision of any remaining embedded tick fragments and associated lesion is neededin order to reduce the likelihood of the development ofgranulomas.
The authors declare no conflict of interest.
REFERENCES
1 Elston DM. Tick bites and skin rashes. Curr Opin Infect Dis.
2010;23:132-8. PMID: 20071986.
2 Castelli E, Caputo V, Morello V, Tomasino RM. Local reactions to tick bites. Am J Dermatopathol. 2008;30:241-8.
PMID: 18496425.
3 Winter LH, Strakosch EA. Tick bites-dermacentor variabilis.
J Invest Dermatol. 1941;4:249-58.
4 Patterson JW, Fitzwater JE, Connell J. Localized tick bite reaction. Cutis. 1979;24:168-9, 172. PMID: 477386.
5 Goldman L. Tick bite granuloma: failure of prevention oflesion by excision of tick bite area. Am J Trop Med Hyg.
1963;12:246-8. PMID: 13948766.

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