Phalangeal microgeodic syndrome and pine processionary caterpillar

ARTICLE

Auteur(s) : Véronique VISEUX¹, Guillaume CHABY¹, Patrick ESQUENET¹, Isabelle BEN TAARIT², Alexandre REMOND², Catherine LOK¹

¹ Department of Dermatology and Venereology, CHU Sud, 80054 Amiens Cedex 1 France. ² Department of Radiology, CHU Sud, 80054 Amiens Cedex 1, France

Article accepted on 05\06\2003

Key words: Phalangeal microgeodic syndrome is an uncommon disease with the first well‐documented cases reported by Maroteaux in 1970 [1]. The manifestations include sub‐acute swelling and redness of fingers and "microgeodic" osteolytic lesions of underlying phalanges. The affection has been described in children from 2 months to 15 years. The etiology is unknown and cases occur frequently in the colder months of the year suggesting that this disease is due to a cold injury [2, 3]. Direct exposure to processionary caterpillars is mentioned in two cases without further fructuous investigations [1, 4]. We report the case of a child with a typical phalangeal microgeodic syndrome, who had previously played with a processionary caterpillar.

Observation

An 11‐month‐old‐girl was admitted in June 1995 for lips and tongue inflammatory edema and erythematous plaques on the chin, right thumb and index finger. She had been surprised chewing a pine processionary caterpillar. Improvement was obtained in 3 days with anti‐histaminic treatment.

Three months later, she presented with a 1‐month history of edematous fingers with mild pain. Erythema of distal phalanges and fusiform swelling of the middle and proximal phalanges were present on both hands (Fig. 1). The body temperature was normal. There were no signs of arthritis or of systemic illness. Routine laboratory data (electrolytes, liver and kidneys functions, amylase) were within normal limits. White blood‐cell count was elevated (14900\mm³) with an increased lymphocyte count (lymphocytes, 54 per cent; segmented polymorphonuclear leukocytes, 37 per cent; eosinophils, 0.7 per cent). ESR was 15 mm\hour. Tests for syphilis, tuberculosis and other causes of osteomyelitis were negative. Complement, C‐reactive protein and angiotensin‐converting enzyme were within normal limits. Rheumatoid factor, anti‐nuclear antibodies and viral serological tests (HIV, hepatitis virus, parvovirus B19) were negative. Radiographs of the hands revealed swelling of soft tissue and small round lytic lesions within the middle and the distal phalanges of several fingers (Fig. 2). Other skeletal radiographs and chest X‐ray were normal. A biopsy of a middle phalanx osteolytic lesion of the right second finger was carried out. Histologic examination showed fibrosis and foreign bodies with hair aspect surrounded by an epithelioid granuloma (Fig. 3). Each hair included a central and a cortical area. Colorations (Ziehl, PAS) were negative. Cultures of the specimen produced no growth of fungi, mycobacteria or routine bacterial flora. Histologic examination of the adjacent skin was normal. A diagnosis of phalangeal microgeodic syndrome was made. When the child was re‐examined at the age of 2 and 3 years, the hands were clinically normal and the radiological lesions had regressed substantially..

Discussion

The clinical and radiologic features of this case represent the same entity reported with details by Maroteaux and named "a microgeodic disease of unknown aetiology affecting the finger phalanges in infants" [1]. Since this description, similar cases have been reported by Japanese authors [2, 5, 6] and more rarely by European authors [7‐9].

Clinical manifestations include sub‐acute swelling and redness of middle and\or proximal phalanges of one or several fingers occurring in an otherwise healthy child. The index and middle fingers are frequently involved, in contrast to distal phalanges, metacarpal regions and feet [5, 6]. The standard radiographs show numerous "microgeodic" osteolytic lesions of the underlying phalanges with various levels of osteosclerosis leading to the diagnosis of PMS when the radiologist is experienced. The prognosis is fairly good and the clinical symptoms regress within several months. Radiographic images disappear in most of cases in several months to years. From a standard radiographic viewpoint, sickle‐cell anemia, syphilis, osteomyelitis, tuberculosis and sarcoidosis must be included in the differential diagnosis because osteolytic lesions are present, however clinical history, associated symptoms, results of laboratory investigations and other associated radiographic lesions are usually observed in these diseases. When the diagnosis remain doubtful, MRI of the fingers could be performed before the bone biopsy. MRI of phalangeal microgeodic syndrome seems to be more sensitive and to have a better specificity than the standard radiographs, showing principally on T1‐weighted spin‐echo lesions with diffuse, inhomogeneous low signal intensity and on T2‐weighted spin‐echo, a high signal intensity. However, more published cases with MR images are necessary to confirm it [10]. Regular survey of the child is necessary and bone biopsy is performed if clinical spontaneous regression in several months is not observed.

The precise etiology is still unknown. Most of the cases occurring sporadically and in wintertime lead some authors to think that this syndrome might be caused by circulatory disturbances in the phalanges exposed to low temperatures [3, 5]. However, this hypothesis is doubtful for the case of Meller et al. [11] occurring in wintertime, in Israel, where winter is very mild and for several European cases occurring in summer [1, 9]. Infectious agents such as parainfluenza and hepatitis A virus have been suspected in Japan [6]. Increased white‐blood cell count and lymphocyte count have been noticed, as in our case, however the viral infection may be casual.

Insect bites or contact with animal hairs within the months preceding the disease are rarely mentioned. Maroteaux‘s patient 3 [1] presented swelling of his fingers and microgeodic lesions after he had been playing with a caterpillar. Bone biopsy disclosed filling of the marrow space with fibrous tissue and one lymphocytic nodule without tuberculosis nor foreign body. Insect stings were evocated by the family doctor in Brijs‘s case [7] but no bone biopsy was performed. In another observation, the patient presented 2 months after he had handled a caterpillar, with cortical erosions and pseudo‐cystic lytic lesions in the finger phalanges, however bone biopsy was not undertaken [4].

Histology in cases for which bone biopsy has been performed usually shows no acute inflammation [1]. Both the bone and bone marrow are affected with necrotic change and proliferation of fibrous connective tissue [2, 11, 12]. There is no growth of fungi, mycobacteria or bacteria on culture. However, a case has been published in which Brucella melitensis was grown from one of the bone lytic lesions, with clinical, radiological and histological pictures very similar to phalangeal microgeodic syndrome [13]. Chronic inflammation, histiocytic and epitheloid cells, with a foreign body corresponding to a caterpillar hair or a sting, and fibrosis have been described by Lagier [14]. This case is similar to our description, however there is no history of contact with a caterpillar.

Pine processionary caterpillars are present in Europe, particularly in the Mediterranean areas. They are one of the major lepidoptera causing specific skin and occular lesions and respiratory signs due to their urticating hairs containing thaumetopœin [15]. To our knowledge, bone affection has not been related with this insect. In South‐Eastern China, pinemoth caterpillar disease is well known to induce generalized symptoms, skin lesions and arthritis. Bone sclerosis, persistant soft tissue swelling, erosions and other bone manifestations have been described too, however without precise physiopathological explanation [16]. In our case, lytic lesions could be explained by the granulomatous reaction to foreign bodies and by irritating substances contained in the hairs.

We describe the first case of phalangeal microgeodic syndrome in a child with a history of playing with a caterpillar and the presence of a caterpillar hair with a granulomatous reaction to foreign bodies in an osteolytic lesion. Several causes for phalangeal microgeodic syndrome are likely and, in Europe, a caterpillar manipulation in the months preceding the disease should be kept in mind. /P>

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