Acta Dermato-Venereologica 99-12CompleteContent | Page 25

1166 INVESTIGATIVE REPORT Unusual Bone Lesions with Osteonecrosis Mimicking Bone Metastasis of Squamous Cell Carcinoma in Recessive Dystrophic Epidermolysis Bullosa Akimasa SAITO 1 , Yoshiyuki NAKAMURA 1 , Ryota TANAKA 1 , Sae INOUE 1 , Naoko OKIYAMA 1 , Yosuke ISHITSUKA 1 , Hiroshi MARUYAMA 1 , Rei WATANABE 1 , Kenji YOSHIDA 2 , Akira ISHIKO 2 , Manabu FUJIMOTO 1 , Satoru SHINKUMA 3 and Yasuhiro FUJISAWA 1 1 Department of Dermatology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, 2 Department of Dermatology, Toho University School of Medicine, Tokyo, and 3 Divisions of Dermatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan Some bone lesions are reported to mimic bone meta- stasis on imaging tests. Herein, we report a case of a 55-year-old Japanese man who presented with a skin tumour on the left lower extremity. He also had a history of recurrent generalized cutaneous blister and erosion formation since childhood. His skin lesions were diagnosed as cutaneous squamous cell carci- noma complicated by recessive dystrophic epidermo- lysis bullosa. Magnetic resonance imaging of the left lower extremity detected multiple focal bone lesions mimicking bone metastases in the left femur and tibia. However, bone biopsy revealed that the bone lesions were osteonecrosis without tumour cells. We suggest that cancer-induced osteonecrosis should be included in the differential diagnosis of bone lesions suspected of being metastases on magnetic resonance imaging. Key words: osteonecrosis; bone metastasis; squamous cell car- cinoma; recessive dystrophic epidermolysis bullosa. Accepted Aug 26, 2019; E-published Aug 27, 2019 Acta Derm Venereol 2019; 99: 1166–1169. Corr: Yoshiyuki Nakamura, Department of Dermatology, Faculty of Medi- cine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan. E-mail: [email protected] W hilst bone metastases may occur in various types of cancer, some bone disorders may mimic bone metastases on imaging tests. We report here a case of unusual bone lesions with osteonecrosis mimicking bone metastases of cutaneous squamous cell carcinoma (cSCC) in a patient with recessive dystrophic epidermo- lysis bullosa (RDEB). CASE REPORT A 55-year-old Japanese man was referred to our depart- ment with a 4-month history of a rapidly growing skin tumour in his left lower extremity. He had a history of recurrent generalized cutaneous blister and erosion formation since childhood. His brother had experienced similar recurrent symptoms, but his parents had not. Physical examination revealed a 20 × 18-cm, ulcerated tumour with a bad odour and grossly abnormal discharge doi: 10.2340/00015555-3303 Acta Derm Venereol 2019; 99: 1166–1169 SIGNIFICANCE We report a case of unusual bone lesions with osteone- crosis mimicking bone metastases of cutaneous squamous cell carcinoma in a patient with recessive dystrophic epi- dermolysis bullosa. In our case, it was speculated that va- rious humoral factors carried by the feeder arteries from the primary cutaneous squamous cell carcinoma lesion and surrounding the multiple chronic wounds and scars associ- ated with recessive dystrophic epidermolysis bullosa might be involved in the development of osteonecrosis. Our case suggests that cancer-induced osteonecrosis should be con- sidered for the differential diagnosis of bone lesions sus- pected of being metastases on imaging tests. around the left knee (Fig. 1a). Poikiloderma, hypopig- mentation and erosions were present on the face, neck, trunk, and extremities, as were some blisters on the trunk (Fig. 1b, c). Skin samples from the blisters demonstrated decreased expression of collagen VII on immunohisto- chemical staining, and hypoplastic anchoring fibrils on electron microscopy compared with a healthy control skin sample (Fig. 1d–g). Direct sequencing analysis of COL7A1 revealed that the patient was compound hete- rozygous for the splice-site (c.2440G>A (p.Gly814Ser)) and recurrent frameshift (c.5819delC (p.Pro1940fs)) mutations (Fig. 1h). RDEB was diagnosed from these findings. Histological analysis of the skin tumour revea- led proliferation of atypical squamous cells with frequent dyskeratosis and mitoses, although the atypia was weak and destructive invasion was not observed (Fig. 1i, j). cSCC was diagnosed from the combined findings of the histological analysis and clinical features showing a significantly large and rapidly growing tumour. Magnetic resonance imaging (MRI) of the left lower extremity revealed that the primary tumour may have extended to near the tibia (Fig. 2a). In addition, multiple focal bone lesions with hypointense signals on the T1- weighted images and hyperintense signals on the T2- weighted images of the left femur and tibia were observed (Fig. 2a, b). Dynamic contrast-enhanced MRI revealed enhancement of the bone lesions with multiple feeder arteries from the primary tumour to the focal bone lesions This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica.