Sir,

Scar sarcoidosis sometimes occurs on previous surgical scars, presenting with infiltration of the scar tissues. Thus, scar sarcoidosis results in the development of plaques or nodules. We, herein, report an unusual case of subcutaneous sarcoidosis under an old surgical scar.

A 75-year-old female was referred to our department for detailed examination of skin lesions of sarcoidosis. She had been diagnosed with chronic heart failure two years previously. Lung computed tomography revealed nodular shadows and mediastinal lymphadenopathy, but ophthalmological examination was normal. Physical examination revealed a surgical scar resulting from intraperitoneal tumor removal thirty years previously, which had flattened and become normal in color, as well as a more recent reddish hypertrophic scar that was the result of a uterine cancer four years previously (Fig. 1a). There were subcutaneous nodules underlying the older scar only (Fig. 1b), with no cutaneous symptoms on the other sites. Laboratory examination revealed normal serum levels of angiotensin converting enzyme and elevated levels of sIL-2R (1131 U/mL, normal <500). Histopathological examination revealed non-caseating epithelioid cell granulomas in the subcutaneous tissue (Fig. 2). Additionally, foreign body granulomas were observed within the granulomatous lesions in the subcutis (Fig. 3). Treatment for cardiac failure with diuretic drugs and antihypertensive drugs was continued, but no treatment was administered for the patient’s lung and skin lesions.

	Figure 1: a) Preexisting surgical scars in a vertical direction on the abdomen, parallel with each other. b) Subcutaneous nodule observed only under the older scar (indicated by the circle).
	Figure 2: Histopathology showing dermal fibrosis and subcutaneous sarcoid granulomas.
	Figure 3: Higher magnification revealing foreign body materials in the giant cells (arrow).

Scar sarcoidosis presents with infiltration of preexisting scars, resulting from trauma, surgery, or scalding, and the clinical features exhibit plaques or dermal papulonodules [1,2]. On the other hand, subcutaneous sarcoidosis occurs most frequently on the extremities, unassociated with scars [3], and subcutaneous nodules restricted to under old scars are uncommon. The co-existence of scar sarcoidosis and subcutaneous sarcoidosis in different locations in a single patient is not rare; however, to the best of our knowledge, only one case of subcutaneous sarcoidosis occurring under a scar has been reported. Singh et al. reported subcutaneous sarcoidosis under an old surgical scar, but without scar sarcoidosis in the dermis [4]. In the present case, the patient had two surgical scars, which were positioned in a vertical direction on the abdomen, parallel with each other. They had been created thirty years and four years previously, with the older scar being skin-colored and flat, and the more recent scar being reddish and slightly hypertrophic. A subcutaneous nodule was only observed under the older scar, whereas no infiltration of the newer scars was observed. Histopathology revealed sarcoid granulomas in the subcutis, and foreign body materials were detected in the giant cells. Although the nature of these materials remains unknown, it is likely associated with the surgery that the patient had undergone thirty years previously, possibly surgical sutures. To date, several cases showing delayed foreign body reactions to suture materials and silica have been reported, with 7-year [5] or 15-year [6] intervals. Our case is unique, developing scar sarcoidosis with an exceptionally long time between the surgery and the foreign body reaction. Scar sarcoidosis typically presents as plaque-type sarcoidosis, with sarcoid granulomas located in the dermis. While subcutaneous sarcoidosis developing under old scars is less common, scar tissues remain susceptible to induced sarcoidosis. Cutaneous scar sarcoidosis is often associated with systemic sarcoidosis [7]. It should be kept in mind that subcutaneous sarcoidosis may develop under preexisting surgical scars.

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