A 37-year-old man comes to the physician with nodules on his hand and forearm. The nodules first appeared about 2 weeks ago on the dorsal aspect of his right index finger. Initially, a small papule formed and drained some clear, odorless material. There was minimal associated pain. The nodule persisted and several days later two other similar nodules formed over the dorsal aspect of his right wrist and distal arm. He has no fever, chills, or constitutional symptoms. The patient works as a landscaper and has installed a lot of moss in terraced yards over the past month. He also hunts and within the past month has dressed rabbits that he has shot. He is in good health, takes no medications, and has no HIV risk factors.
Vital signs are normal. Cardiopulmonary, abdominal, and neurologic examinations are normal. There are 3 tender papules on top of the dorsal aspects of the right index finger, wrist, and the distal right upper extremity. One open nodule has a small crust on the top. There are no other cutaneous lesions and no adenopathy.
A sample is obtained for biopsy and culture. The biopsy shows mixed pyogenic and granulomatous inflammation. Gram stain, acid-fast/partial acid-fast, silver methenamine, and periodic acid-Schiff stains (PAD) are negative. Cultures are pending.
What is the most likely diagnosis in this patient?

Question

A 37-year-old man comes to the physician with nodules on his hand and forearm.  The nodules first appeared about 2 weeks ago on the dorsal aspect of his right index finger.  Initially, a small papule formed and drained some clear, odorless material.  There was minimal associated pain.  The nodule persisted and several days later two other similar nodules formed over the dorsal aspect of his right wrist and distal arm.  He has no fever, chills, or constitutional symptoms.  The patient works as a landscaper and has installed a lot of moss in terraced yards over the past month.  He also hunts and within the past month has dressed rabbits that he has shot.  He is in good health, takes no medications, and has no HIV risk factors.
Vital signs are normal.  Cardiopulmonary, abdominal, and neurologic examinations are normal.  There are 3 tender papules on top of the dorsal aspects of the right index finger, wrist, and the distal right upper extremity.  One open nodule has a small crust on the top.  There are no other cutaneous lesions and no adenopathy.
A sample is obtained for biopsy and culture.  The biopsy shows mixed pyogenic and granulomatous inflammation.  Gram stain, acid-fast/partial acid-fast, silver methenamine, and periodic acid-Schiff stains (PAD) are negative.  Cultures are pending.
What is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

This patient most likely has the lymphocutaneous form of sporotrichosis. Sporotrichosis is a subacute to chronic infection caused by the dimorphic fungus Sporothrix schenckii, whose natural habitat is on the bark of trees, shrubs, and garden plants, and on plant debris in soil. Lymphocutaneous sporotrichosis is the most commonly encountered form of sporotrichosis, with the typical host being a healthy individual with an outdoor hobby or occupation (eg, landscaping, rose gardening). Lymphocutaneous sporotrichosis begins with inoculation of contaminated moss, soil, or other organic material into the skin or subcutaneous tissue. Days to weeks later, a reddish nodule forms at the site of inoculation (eg, thorn prick). This primary lesion typically ulcerates but can remain nodular. Drainage from the lesion is not grossly purulent and has no odor. Adenopathy and systemic signs of infection are also usually absent. Similar lesions subsequently develop more proximately and follow a lymphatic chain (referred to as nodular lymphangitis). Biopsies typically show a mixed pyogenic and granulomatous inflammation. Fungal stains (silver methenamine silver, PAD) are often negative because the number of infecting organisms is frequently small. Culture is the gold standard for establishing a diagnosis of sporotrichosis. Itraconazole is the drug of choice for treatment. (Choice A) Mycobacterium marinum infection often follows abrasions to an extremity that occur in nonchlorinated water ("fish tank granuloma"). Fishermen, oyster handlers, swimmers, and aquarium workers are predisposed to infection. Clinical presentation can be similar to sporotrichosis. Microscopic examination shows acid-fast organisms. (Choice B) Although rare, a lymphocutaneous form of Nocardia infection (particularly with Nocardia brasiliensis) can affect immunocompetent hosts and results from direct inoculation of the organism into the skin following traumatic injury. Referred to as sporotrichoid nocardiosis, it can closely resemble sporotrichosis. Diagnosis of Nocardia infection is difficult; however, a presumptive diagnosis can be made if partially acid-fast, filamentous, branching rods are seen in clinical specimens. (Choice C) Pyoderma gangrenosum (PG) usually occurs within the context of a systemic disorder, most commonly inflammatory bowel disease, arthropathies, and hematologic malignancies. The most frequent presentation of ulcerative pyoderma gangrenosum is a rapidly developing, painful, purulent ulcer with a violaceous and undermined border. Fever may also be present. Pyoderma gangrenosum (PG) (Choice E) The majority of patients with tularemia present with ulceroglandular disease. Patients typically report recent handling of animals (eg, rabbits) or exposure to ticks. Affected patients usually present with fever and a single erythematous papulo-ulcerative lesion with a central eschar. The skin lesion is accompanied by tender regional lymphadenopathy. Nodular lymphangitis is a rare manifestation of tularemia. Educational objective: The initial lesion of lymphocutaneous sporotrichosis is a reddish nodule that later ulcerates and appears at the site of a thorn prick or other skin injury. From the site of inoculation, the fungus spreads along the lymphatics forming additional subcutaneous nodules and ulcers. Definitive diagnosis is made by culture, and itraconazole is the drug of choice for treatment. __________ References: Sporothrix schenckii and sporotrichosis. (http://www.ncbi.nlm.nih.gov/pubmed/21976602)

A 37-Year-Old Man Comes to the Physician with Nodules on His