WBR0326
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Hematology |
| Prompt | [[Prompt::An 13 year old girl is brought to the physician's office for excessive thirst , frequent urination and weight loss. Upon further questioning, she reports new raised scalp lesions that are increasing in number. Physical examination is remarkable for skull lesions, cervical lymphadenopathy, and exophthalmus. CT scan shows osteolytic coalescent lesions of the skull with a "georgraphical skull" appearance. Biopsy of the skin lesions shows dermal infiltration of clustering cells with large ovoid pink cytoplasm under light microscopy. Immunofluorescence shows positive staining for S100, and CD1a. Electron microscopy shows the presence of pentalaminar membranous organelles in the cytoplasms near the nuclear membrane that resemble tennis rackets. What is the most likely diagnosis?]] |
| Answer A | AnswerA::Langerhan's cell histiocytosis |
| Answer A Explanation | AnswerAExp::The patient is presenting with classical features of Langerhan's cell histiocytosis |
| Answer B | AnswerB::Schwannoma |
| Answer B Explanation | AnswerBExp::Schwannoma may have S100 positive staining, but the rest of the findings cannot be explained by schwannoma. |
| Answer C | AnswerC::Diabetes insipidus |
| Answer C Explanation | AnswerCExp::Diabetes insipidus is classically found as part of the Langerhan's cell histiocytosis syndrome, but is not an isolated diagnosis in this case. |
| Answer D | AnswerD::Mastocytosis |
| Answer D Explanation | AnswerDExp::Mastocytosis may be in the differential diagnosis of Langerhan's cell histiocytosis. However, it cannot explain all the findings in this patient. |
| Answer E | AnswerE::Wiskott-Aldrich syndrome |
| Answer E Explanation | [[AnswerEExp::Patients with Wiskott-Aldrich syndrome (WAS) often have thrombocytopenic purpura, eczematous skin lesions, and recurrent infections, all of which may be present in Langerhan's cell histiocytosis. As such, WAS may be in the differential diagnosis of Langerhan's cell histiocytosis. However, WAS cannot explain all the patient's clinical findings.]] |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::Langerhan cell histiocytosis is a cancer-like heterongeous group of diseases that are characterized by the presence of Langerhans cells, which are epidermal dendritic cells. These cells are often called "nerve cells of the skin". Langerhan's cell histiocytosis was once termed histiocytosis X in the past due to the unclear etiology of the disease. Since the description of Langerhan's cells, the disease is now called "Langerhan's cell histiocytosis".
In fact, the disease is a group of diseases that share the same pathological features: Hand-Schuller-Christian disease (HSC), eosinophilic granuloma, and Letterer-Siwe disease are all subgroups of Langerhan's cell histiocytosis. The patient in the vignette has the classical clinical presentation of HSC disease, characterized by the triad of: diabetes insipidus, exophthalmus, and lytic bony lesions. Other systemic signs and symptoms may be present, such as lymphadenopathy, pulmonary findings, hepatosplenomegaly etc. The disease is best diagnosed pathologically. Light microscopy shows characteristic Langerhan's cells, which are cells with large ovoid pink cytoplasm that infiltrate diffusely the dermal layer resembling a granuloma. Immunofluoresence shows classical staining for C1a and S100. Electron microscopy shows characteristic "Birbeck granules" that resemble tennis rackets. Birbeck granules are defined as pentalaminar membranous organelles in the cytoplasms located near the nuclear membrane. Prognosis is dependent on the patient's age, systemic involvement, and response to therapy. Treatment varies widely between different diseases is still controversial, but may include steroids or ultraviolet phototherapy for skin lesions, bisphosphonates for bone lesions, and chemotherapy for systemic involvement. Educational Objective: Langerhan's cell histiocytosis is characterized by the presence of Langerhan's cells on pathology, positive staining for CD1a and S100. Electron microscopy shows characteristic Birbeck granules, which resemble tennis rackets. References:
|
| Approved | Approved::No |
| Keyword | WBRKeyword::Langerhan's, WBRKeyword::cell, WBRKeyword::histiocytosis, WBRKeyword::X, WBRKeyword::langerhan, WBRKeyword::birbeck, WBRKeyword::granule, WBRKeyword::granules, WBRKeyword::tennis, WBRKeyword::racket, WBRKeyword::S100, WBRKeyword::C1a, WBRKeyword::stain, WBRKeyword::dendritic, WBRKeyword::dendrite, WBRKeyword::skull, WBRKeyword::lesion, WBRKeyword::osteolytic, WBRKeyword::diabetes, WBRKeyword::insipidus, WBRKeyword::exophthalmus |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |