Pilonidal Disease on the Dorsum of the Hand and Sole of the Foot Diagnosed by Superficial Echography.

Sir,

Pilonidal disease (PD) involves a subcutaneous sinus, cystoma, and granuloma with tissues reacting to foreign bodies containing hair. PD commonly occurs in the sacral region in adult men. It was also referred to as pilonidal sinus or a pilonidal cyst; however, it is not always histologically accompanied by a fistula or cystoma. In 1945, Granet and Ferguson renamed it to PD, a collective term for these pathological changes.[1] The risk of PD between fingers 2 to 4 was associated with some occupations, such as barbers, sheep shearers, milkers, and dog groomers.[234] Here, we report two cases of PD: one on the dorsum of a barber's hand, and the other on the sole of a housewife's foot. These are the first reported cases of PD occurring at these sites.

Case 1: A 48-year-old right-handed male barber presented with a crimson nodule on the dorsum of his right hand accompanied by sensations of heat and pain after repeated improvement and aggravation for 3 months. He had no underlying diseases. At the first visit, a tender 1.5-cm crimson nodule was noted on the dorsum of his right hand [Figure 1a]. Superficial echography revealed a hypoechoic region with an obscure boundary where a 7-mm hyperechoic line was observed [Figure 1b]. Therefore, the patient was diagnosed with PD. The skin nodule shrank after treatment with oral antibiotics and was eventually removed surgically after 1 month. During the operation, an approximately 7-mm hair that was consistent with the echographic findings was detected subdermically and excised [Figure 1c].

Figure 1

(a) A crimson nodule on the dorsum of the right hand. (b) A 7-mm hyperechoic line. An ultrasonogram was performed using a 12 MHz liner transducer in B mode. (c) A subcutaneously-embedded hair

Case 2: A 53-year-old full-time housewife without any underlying diseases presented with redness and swelling of an area <2 cm at the base of the 4th toe of her left foot. This appeared repeatedly for 2 months. At the first visit, a tender, elastic, and hard subcutaneous nodule was detected [Figure 2a]. Superficial echography revealed an approximately 8-mm linear, arc-shaped hyperechoic region [Figure 2b]. With suspicion of PD or some sort of subcutaneous foreign object, surgical excision was performed, and hair was detected subcutaneously and removed [Figure 2c].

Figure 2

(a) A hard and tender subcutaneous nodule at the base of the 4th left toe. (b) An approximately 8-mm linear, arc-shaped hyperechoic region. The ultrasonogram was performed using a 12 MHz liner transducer in B mode. (c) A hair within the adipose tissue. After excision, the hair measured about 2 cm

In both cases, inflammatory cell infiltration and fibrotic tissue hyperplasia from the dermis to adipose tissue were observed histopathologically [Figure 3a and 3b].

Figure 3

(a) Case 1, (b) Case 2. In both cases, inflammatory cell infiltration and fibrotic tissue hyperplasia from the dermis to adipose tissue were observed and the hair follicles were removed during surgery; hence, they could not be seen in the tissue (hematoxyline-eosin stains; ×10)

Ciftci and Abdurraham investigated 949 PD cases and reported that only 2.2% of lesions were found outside the sacral region; these sites included the scalp (n = 2), cervical region (n = 2), armpit (n = 5), thoracic region (n = 3), abdominal wall (n = 5), and inguinal region (n = 4).[5] Due to occupational hand eczema in Case 1 and a history of refractory tinea pedis in Case 2, both patients had scratched the hand/foot repeatedly. Therefore, presumably PD developed because of hair trapped in the eroded skin or during ulcer formation due to scratching, which remained during epithelization and was embedded subcutaneously.

If the site of the lesion is not where PD occurs commonly, PD may often be misdiagnosed as a purulent atheroma or subcutaneous abscess. If a crimson skin nodule occurs repeatedly even after treatment with antibiotics or incision and drainage, echography is necessary.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.