October 7th 2025
Psoriasis, lichen planus, and pityriasis rosea share overlapping presentations and comorbidities, but distinct pathophysiologies require accurate diagnosis and tailored therapeutic approaches.
Seborrheic Dermatitis of the Scalp
September 14th 2005The entire scalp of this 1-month-old boy shows the diffuse yellow scaling of seborrheic dermatitis. Called “cradle cap” in infants, this dermatitis typically begins on the scalp during the first 3 months and may spread over the entire face. An associated stubborn diaper rash may develop in some infants.
Metastatic Squamous Cell Carcinoma
September 14th 2005Shortly after arriving from Puerto Rico, a 59-year-old man presented with right-sided frontal head pain and decreased vision in his right eye. He was concerned about a “sore” that first developed 9 months earlier on his head. The patient denied fever, chills, and syncope.
Pyogenic Granuloma on the Thumb of a 53-Year-Old Woman
September 14th 2005This red papule developed 6 months ago at the base of a 53-year-old woman's thumb. The lesion was asymptomatic, but it bled easily when traumatized. It was treated definitively with surgical excision, and the biopsy report was consistent with the clinical diagnosis of pyogenic granuloma. This most commonly appears on the face or fingers and may result from minor trauma.
Pyoderma Gangrenosum Surrounding Colostomy Stoma in a 64-Year-Old Woman With Crohn Disease
September 14th 2005A painful skin eruption surrounding her colostomy stoma had appeared several months ago and was slowly increasing in size, complained a 64-year-old woman with Crohn's disease. The lesion consisted of several coalescent ulcers with a yellow, fibrinoid base and a violaceous, undermined border.
Tinea Pedis and Reactive Eruptions
September 14th 2005A 42-year-old woman had had athlete's foot for years, but the condition suddenly worsened when inflamed, pruritic vesicles appeared on both feet. A few days later, tiny, mildly itchy vesicles erupted on her palms; the rest of the hands were not involved. One week after the palmar eruptions, the patient noted 2 round, reddish brown, asymptomatic 3-cm macules on her trunk. These lesions had faint scaling on the trailing edge of the slowly advancing arciform borders.
Rheumatoid Nodules in a Woman With 40-Year History of Rheumatoid Arthritis
September 14th 2005A 76-year-old woman had a 40-year history of rheumatoid arthritis (RA). She had repeatedly refused treatment with disease-modifying drugs, including methotrexate. Nodules began to develop 15 years after the initial diagnosis; they recurred after surgical removal.
Rheumatoid Nodules in a 65-Year-Old Woman
September 14th 2005A 65-year-old woman, who was confined to a wheelchair because of severe rheumatoid arthritis, was concerned about nodules that had erupted on her fingers and hands during the previous 3 weeks. Her medical history included colon cancer, chronic renal insufficiency, anemia, and hypertension. The nonpruritic nodules were painful when they began to form under the skin; however, once they erupted, the pain disappeared.
Rheumatoid Arthritis: Cutaneous Lesions
September 14th 2005Various types of cutaneous lesions may occur in association with RA, including rheumatoid nodules, rheumatoid neutrophilic dermatitis, vasculitis, palpable purpura, and pyoderma gangrenosum. Many of these manifestations-including rheumatoid nodules-are specific for RA. The presence of these nodules is associated with seropositive disease and with a more severe, erosive clinical presentation. The nodules appear in 20% to 30% of patients with RA. Sites of predilection are those subject to shear stress, including the subcutaneous tissues over the extensor aspects of the elbow region, over the sacrum in bedridden persons, and at the pericardial and pleural surfaces.
Pyoderma Gangrenosum: What to Include in the Differential Diagnosis
September 14th 2005Pyoderma gangrenosum (PG) is a chronic, recurrent condition characterized by cutaneous ulceration. In half of patients, PG is associated with an underlying illness, such as inflammatory bowel disease, RA, SLE, or a lymphoproliferative disorder.