Giant cutaneous squamous cell carcinoma of the popliteal fossa skin: A case report

Abstract

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is a common malignant hyperplasia of the skin epithelium. However, cSCC progressing to giant squamous cell carcinoma of the popliteal fossa skin has not been reported. We used full-thickness skin graft from the lower left quadrant of the abdomen to reconstruct the popliteal fossa skin defect in our patient.

CASE SUMMARY

A 64-year-old woman presented with a 3-year history of a progressively enlarged integumentary tumor located on her left popliteal fossa, which was surgically treated. The resultant defect (15 cm × 25 cm) was repaired using full-thickness skin graft from the lower left quadrant of the abdomen.

CONCLUSION

Full-thickness skin graft is a good choice to repair popliteal fossa defect.

Key Words: Giant cutaneous squamous cell carcinoma; Popliteal fossa skin; Case report

Core Tip: We report an exceedingly rare case of giant cutaneous squamous cell carcinoma (maximum diameter > 5 cm), which presented as skin invasion of the popliteal fossa that was excised with optimal clinical result.

INTRODUCTION

Cutaneous squamous cell carcinoma (cSCC) is a non-melanoma skin and keratinocyte cancer, accounting for 20% of all skin cancers, and it is the second most common cancer worldwide[1]. Unfortunately, cSCC is not included in the national cancer registry in the United States, which makes it difficult for us to know the exact morbidity and mortality in China. European data show that the age-standardized incidence of cSCC is 9 to 96 cases per 100000 male residents and 5 to 68 cases per 100000 female residents (2002-2007 estimate)[2-4].

Although cSCC is mostly a benign tumor, it can locally infiltrate and metastasize. The 10-year survival rate of patients with cSCC is over 90%, but when metastasis occurs, the survival rate drops sharply[5]. The frequency of lymph node metastasis is about 4%, and the mortality is close to 2%. Because of the high incidence of cSCC, it has a significant impact on the overall mortality[6]. Furthermore, most cSCCs can be completely removed by surgery. cSCC of the popliteal fossa skin, which is a very rare site, is closely related to the knee joint and important neurovascular system, posing a surgical challenge for reconstruction. Herein, we report an exceedingly rare case of giant cSCC (maximum diameter > 5 cm), which presented as skin invasion of the popliteal fossa that was excised with optimal clinical result.

CASE PRESENTATION

Chief complaints

Three-year history of pain and mobility problems due to a progressively enlarged integumentary tumor located on the left popliteal fossa.

History of present illness

In June 2020, a 64-year-old woman presented with a 3-year history of pain and mobility problems due to a progressively enlarged integumentary tumor located on her left popliteal fossa.

History of past illness

This patient had no history of chronic diseases, such as hypertension, hyperuricemia, hyperlipidemia, and coronary heart disease.

Personal and family history

The patient was a non-smoker and had no family history of cSCC.

Physical examination

Physical examination showed an erythematous, nodular, protruding, ulcerative, mainly necrotic, foul smelling, cauliflower-like, firm skin tumor measuring 15 cm × 20 cm on the left popliteal fossa (Figure 1A). However, no significant lymph node or distant metastases were identified.

Figure 1 Before the surgery. A: A huge erythematous nodular ulcerative skin tumor, measuring approximately 15 cm × 20 cm, was located on the left popliteal fossa; B: Computed tomography scan of the popliteal fossa.

Laboratory examinations

The laboratory results revealed that the level of squamous cell carcinoma antigen was 20 ng/mL, the C-reactive protein level was 15.5 mg/L, and the erythrocyte sedimentation rate was 42 mm/h. Other laboratory results were within the normal range.

Imaging examinations

Computed tomography showed that the tumor had infiltrated deep into the muscular layer of the left popliteal fossa, but not the skeletal layer (Figure 1B).

FINAL DIAGNOSIS

Giant cSCC of the popliteal fossa skin.

TREATMENT

After popliteal fossa tumor excision and skin grafting, the tumor was totally excised. The tumor infiltrated the muscular layer and a 4 cm margin of muscular tissue was excised with the tumor. The final surgical defect measured 15 cm × 25 cm (Figure 2A and B). The surgical defect was repaired with a full-thickness skin graft from the lower left quadrant of the abdomen.

Figure 2 After extirpating the tumor, the final surgical defect on the left popliteal fossa measured 25 cm × 15 cm. A: The surgical defect in the left popliteal fossa was 25 cm long; B: The surgical defect in the left popliteal fossa was 15 cm wide; C: As seen on day 4 after reconstruction, the surgical defect on the left popliteal fossa was repaired by full-thickness skin grafting; D: Appearance of the full-thickness skin repair of the left popliteal fossa on day 15 after reconstruction; E: Appearance of the full-thickness skin repair of the left popliteal fossa at the 1-year follow-up.

OUTCOME AND FOLLOW-UP

After surgery, the patient’s condition significantly improved (Figure 2C and D). Hematoxylin and eosin-stained section of the surgical specimen revealed an invasive, infiltrative well-differentiated cSCC (Figure 3). The patient was discharged 1 mo after operation, and had no recurrence and good wound healing after surgery. The patient was followed for one year after surgery (Figure 2E), without recurrent symptoms.

Figure 3 Photomicrographs of the tumor. A: Scattered squamous cells with dyskeratosis and mitotic infiltrates (H&E staining, 40 × magnification); B: Numerous squamous cells with dyskeratosis and mitotic infiltrates (H&E staining, 100 × magnification); C: Squamous cells in the periphery of the tumor (H&E staining, 400 × magnification).

DISCUSSION

Although most cSCC cases have a good prognosis after surgical resection[7], 3.7%-5.2% of patients have lymph node metastasis, and 1.5%-2.1% of patients die of cSCC[8]. Although these incidences are relatively low compared with those of many other malignant tumors, the absolute number of cSCC patients with lymph node metastasis is estimated to be 5604 to 12572 in the United States alone[9]. In addition, the estimated number of cSCC-related deaths per year is between 3932 and 8791, and its upper limit is close to the number of melanoma-related deaths per year. Thus, it is important to identify such aggressive cSCC cases in time, which can guide additional testing and treatment to improve the prognosis[7].

Old age, fair skin, long-term sun exposure, long-term immunosuppression, and previous skin cancer diagnosis are all important risk factors for cSCC[10]. In addition, long-term skin inflammation seems to contribute to the development of cSCC, such as chronic wound, ulcer, sinus tract, burn, or scar[11]. This patient developed cSCC mainly due to repeated skin ulceration, leading to local chronic inflammation and popliteal squamous cell carcinoma, which not only affects the functional recovery of knee joint but also increases the probability of malignant degeneration and the difficulty of popliteal defect reconstruction.

Besides Bowen disease, keratoacanthoma (KA), and invariant cSCC classic variant described above, the pathological tissues of cSCC also have several types, such as fibroproliferative, spindle cell, keratolytic, pseudovascular, verrucous, wedge-shaped epithelioma, adenosquamous cell and neurotrophic cSCC[12]. Disordered maturation of atypical keratinocytes, single cell keratinization, nuclear pleomorphism, atypical mitosis, and multi-nucleated tumor cells appear in all epidermal layers, but the basal layer remains unchangedI[13]. KA is a symmetrical keratinocyte hyperplasia with limited proliferation, and its central horn plug and epidermis extend to the tumor. Histologically, invasive cSCC is characterized by atypical and abnormal keratinocytes, hyperchromic and pleomorphic nuclei, and atypical mitotic cells. Well-differentiated cSCC usually has horny pearls and single cell keratinization, while poorly differentiated cSCC usually lacks keratinization, and has many atypical mitoses and mixed inflammatory infiltration.

Pathological examination showed numerous squamous cells with keratosis and mitotic infiltration[13]. Considering that it was invasive cSCC with keratosis and no lymph node metastasis was found in our case, we performed surgery for complete tumor resection and skin grafting, and advised the patient to undergo regular postoperative reexamination.

The resection of cSCC at the popliteal fossa involves joint movement and numerous blood vessels and nerves. Therefore, it is critical to protect the important neurovascular system and prevent secondary scar contraction based on extensive activities of the popliteal fossa, which may be manifested as external aesthetic distortion and popliteal fossa retraction, thus seriously damaging the shape and function[14]. We chose a full- thickness skin graft from the lower left quadrant of the abdomen to repair the popliteal fossa defect. Full-thickness skin graft can survive on fresh sterile wounds or infected granulation wounds due to its characteristics of thin skin and strong vitality[15]. Additionally, the donor area is scar-free and cannot be easily infected[16]. In the present case, the patient could perform normal daily activities, without severe postoperative pain or any complications. Therefore, full-thickness skin repair is suitable for patients with popliteal cSCC who need extensive tumor resection, with fewer complications and faster postoperative recovery.

CONCLUSION

Full-thickness skin graft is a good alternative for the repair of popliteal fossa defects.