Co-occurrence of LCH and RDD is a rare phenomenon. Various explanations, including the role of chemotherapy, are suggested based on our and several previously reported cases.

CASE 1: A 64-year-old, otherwise healthy woman was referred to the surgery clinic for a presumed umbilical hernia. On physical examination, a cutaneous nodule was noted on the umbilical region and the patient was referred to the dermatology clinic. The patient was reexamined and an erythematous nodule was observed in the umbilicus measuring 2.5 cm in diameter. The patient denied pain, change in bowel habits, or weight loss. There were no other abdominal masses, no sign of ascites, and no regional lymphadenopathy. A skin biopsy from the nodule showed mucinous adenocarcinoma. Immunohistochemical staining was positive for carcinoembryonic antigen, and negative for cytokeratin (CK)7 and CK20. These results were consistent with a Sister Mary Joseph's nodule and led to the diagnosis of an occult colon carcinoma. The patient had no risk factors for colorectal carcinoma. The patient underwent surgery in another hospital, and died 3 months after the initial diagnosis of Sister Mary Joseph's nodule. CASE 2: A 73-year-old woman was referred to the dermatology clinic for evaluation of a painful, ulcerated, 3-cm lesion in the umbilicus (Figure 1). She was otherwise asymptomatic. A skin biopsy showed neoplastic glandular cells infiltrating among collagen bundles (Figure 2). Stainings for mucin and for CK7 were positive, while staining for CK20 was negative. An abdominopelvic CT scan demonstrated a 3.5-cm space-occupying lesion in the liver. Results of gastroscopy, colonoscopy, chest computed tomographic (CT) scan, and mammography were normal. Serum levels of the tumor-associated protein CA125 were elevated to 164 units, while those of CA 19-9 and carcinoembryonic antigen were within normal range. A gynecologic examination and a transvaginal ultrasound were normal. The patient had no personal or family history of any malignancy or any risk factors for developing a carcinoma. The patient was scheduled for a palliative resection of the umbilical nodule, combined with a laparoscopic inspection in search of the undetected primary tumor. She refused surgery and was lost to follow-up. She died 4 months after the initial diagnosis of umbilical metastasis. CASE 3: A 51-year-old man was aware of a silent mass in his umbilicus for 2 years without seeking medical advice. Following 2 weeks of increasing pain in this area, he was referred to the emergency room for a suspected incarcerated umbilical hernia. Surgery revealed a mass attached to the fascia and peritoneal fat. The mass was removed and diagnosed as a poorly differentiated adenocarcinoma, staining positively for carcinoembryonic antigen, and negatively for CK20, CK7, prostate-specific antigen, and prostatic acid phosphatase. Both gastroscopy and colonoscopy failed to detect the primary tumor. An abdominopelvic CT scan was normal, but a CT scan of the chest disclosed a nodule measuring 2.5 x 1.5 cm in the lower lobe of the right lung. On bronchoscopy, it was found to be an invasive adenocarcinoma, consistent with a primary tumor of the lung. The patient was a heavy smoker (45 pack-...

Minocycline can possibly serve as a fluorescent probe in the diagnosis of all types of minocycline-induced cutaneous hyperpigmentation.