A 19-year-old man comes to the office due to a painful subcutaneous forearm nodule. Two weeks earlier, he received a laceration on his left forearm while playing soccer and had sutures placed. The lesion is biopsied, and results are shown in the image below: Which of the following is most likely responsible for this patient's condition?

Question

A 19-year-old man comes to the office due to a painful subcutaneous forearm nodule.  Two weeks earlier, he received a laceration on his left forearm while playing soccer and had sutures placed.  The lesion is biopsied, and results are shown in the image below:  Which of the following is most likely responsible for this patient's condition?

Quizplus · Accepted Answer

11ec160b_37c9_b58d_9249_9b6811d532fb_MD0001_00 Foreign bodies (eg, retained sutures) can elicit a granulomatous response, seen clinically as a tender, erythematous, brown or purple papule, nodule, or plaque. Granulomas are characterized microscopically by aggregates of activated macrophages that assume an epithelioid appearance. They are often surrounded by a rim of lymphocytes that synthesize the cytokines responsible for granuloma maintenance. Multinucleated giant cells, derived from the fusion of several macrophages, can also be found in granulomas. Granuloma formation is a complex process that occurs over several days to weeks in response to an antigen that cannot be eradicated by more acute inflammatory mechanisms (eg, killing by neutrophils). As infiltrating macrophages engulf the antigenic debris, material resistant to digestion persists in the cytoplasm and causes macrophage activation. This results in further macrophage maturation and formation of a granuloma, which walls off the offending agent. (Choice A) Excess granulation tissue formation (hypergranulation) usually occurs in a wound left to heal by secondary intention. Light microscopy would show proliferation of fibroblasts, collagen deposition, inflammatory cells, and numerous capillaries. (Choice B) Marjolin ulcer is an aggressive, ulcerating squamous cell carcinoma that presents in an area of previously traumatized, chronically inflamed, or scarred skin. Malignant transformation often occurs long after the initial trauma, usually >10 years later. Histology would show dysplastic keratinocytes and keratinization. (Choice C) The remodeling phase of wound healing is characterized by fibrosis (scar formation) and starts the second week after injury. During this phase, active fibroblasts synthesize collagen, elastin, and other components of the connective tissue matrix. (Choice D) The inflammatory phase of wound healing consists of the movement of neutrophils (within the first 24 hours) and macrophages (within 2-3 days) to the damaged area, with phagocytosis of necrotic debris and bacterial contaminants. Persistent neutrophil activity in a wound would result in an abscess and/or pus drainage rather than granuloma formation. Educational objective: Granulomatous inflammation is a form of chronic inflammation characterized by aggregates of activated macrophages that assume an epithelioid appearance. Persistent granulomatous inflammation with subsequent fibrosis can cause organ dysfunction, which is seen in a number of granulomatous diseases.

A 19-Year-Old Man Comes to the Office Due to a Painful